a / V \\ 0-' MUSEUM OF VICTORIA 17469 I Plate I. A MANUAL of tbm rUDY OF INSECTS PV JOHN HENRY COMSTOCK /’ .-r*i s'fT =■« C>n*f!l • >.-r ifity : , . . : N . ORD COMSTOCK - V.- imruan We.*/ ■/£•’:; v a*v ^rvu-mermS OBDihon ituaca, n. v. H E COMSTOCK PU B \. ! i C ; ; V Plate 1 rUkT'Wv?)MSFI)M I'ELRnufcWf A MANUAL OF THE STUDY OF INSECTS BY JOHN HENRY COMSTOCK Professor of Entomology in Cornell University AND ANNA BOTSFORD COMSTOCK Member of the Society of American Wood-Engravers ©etoenteentb OBDftton ITHACA, N. Y. THE COMSTOCK PUBLISHING COMPANY 1923 Copyright, 1895, BY JOHN HENRY COMSTOCK. v PRINTED IN U.S.A. PREFACE. FOR many years the most pressing demand of teachers and learners in entomology in this country has been for a handbook by means of which the names and relative affini¬ ties of insects may be determined in some such way as plants are classified by the aid of the well-known manuals of botany. But, as the science of entomology is still in its infancy, the preparation of such a handbook has been im¬ possible. Excellent treatises on particular groups of insects have been published ; but no general work including analyt¬ ical keys to all the orders and families has appeared. It is to meet this need that this work has been prepared. The reader must not expect, however, to find that de¬ gree of completeness in this work which exists in the man¬ uals of flowering plants. The number of species of insects is so great that a work including adequate descriptions of all those occurring in our fauna would rival in size one of the larger encyclopaedias. It is obvious that such a work is not what is needed by the teachers and students in our schools, even if it were possible to prepare it. An elementary work on systematic entomology will always of necessity be re¬ stricted to a discussion of the characteristics of the orders and families, and descriptions of a few species as illustrations. Complete synopses of species will be appropriate only in works treating of limited groups. It is believed, therefore, that it would not be wise to materially change the scope of • iii IV PREFACE . the present work even if it were possible to describe all of our species. Although much pains has been taken to render easy the classification of specimens, an effort has been made to give the mere determination of the names of insects a very sub¬ ordinate place. The groups of insects have been fully char¬ acterized, so that their relative affinities may be learned ; and much space has been given to accounts of the habits and transformations of the forms described. As the needs of agricultural students have been kept constantly in view, those species that are of economic importance have been described as fully as practicable, and particular attention has been given to descriptions of the methods of destroying those that are noxious, or of preventing their ravages. An effort has been made to simplify the study of in¬ sects as much as possible without sacrificing accuracy in the descriptions. Only such morphological terms have been used as were necessary to accomplish the object of the book in a satisfactory manner. And so far as possible a uniform nomenclature has been used for all orders of insects. The fact that writers on each order of insects have a peculiar nomenclature has been a serious obstacle to the progress of entomology ; this is especially true as regards the nomen¬ clature of the wing-veins. It has been necessary for the student in passing from the study of one order of insects to that of another to learn a new set of terms; and in many cases writers on a single family have a peculiar nomenclature. The present writer has endeavored to remove this obstacle by making a serious study of the homologies of the wing-veins, and by applying the same term throughout the work to homologous veins. The result is that the student is required to learn only one set of terms ; and in applying these terms there will be brought to his attention in a forci¬ ble manner the peculiar modifications of structure charac¬ teristic of each order of insects. Heretofore, with a differ¬ ent nomenclature for the wing-veins of each order such a PREFACE. V comparative study of the various methods of specialization has been beyond the reach of any but the most advanced scholars. The principal features of the method of notation of wing- veins proposed by Josef Redtenbacher has been adopted. But as the writer’s views regarding the structure of the wings of primitive insects are very different from those of Redtenbacher, the nomenclature proposed in this book is to a great extent original. The chief point of difference arises from the belief by the present writer that veins IV and VI do not exist in the Lepidoptera, Diptera, and Hymenoptera ; and that, in those orders where they do exist, they are secondary developments. The reasons for this be. lief are set forth at length in my essay on Evolution and Taxonomy. In this essay there was proposed a new classification of the Lepidoptera, which was the result of an effort to work out the pliylogeny of the divisions of this order. This classi¬ fication has been further elaborated in the present work. In the other orders but few changes have been made from the more generally accepted classifications. It is more than probable however, that when the taxonomic principles upon which this classification of the Lepidoptera is based are ap¬ plied to the classification of the other orders radical changes will be found to be necessary. A serious obstacle to the popularization of Natural His¬ tory is the technical names that it is necessary to use. In order to reduce this difficulty to a minimum the pronuncia¬ tion of all of the Latin terms used has been indicated, by dividing each into syllables and marking the accented syllable. In doing this the well-established rules for the division of Latin words into syllables have been followed. It seems necessary to state this fact in order to account for differences which exist between the pronunciations given here and some of those in certain large dictionaries recently published in this country. VI PREFACE . Nearly all of the wood-cuts have been engraved from nature by the Junior Author. As the skill which she has attained in this art has been acquired during the progress of the work on this book, some of the earlier-made illustra¬ tions do not fairly represent her present standing as an engraver. But it does not seem worth while to delay the appearance of the book in order to re-engrave these figures; especially as it is believed that they will not be found lack¬ ing in scientific accuracy. The generous appreciation which the best engravers have shown towards the greater part of the work leads us to hope that it will be welcomed as an important addition to entomological illustrations. Although the chief work of the Junior Author has been with the pencil and graver, many parts of the text are from her pen. But in justice to her it should be said that the plan of the book was changed after she had finished her writing. It was intended at first to make the book of a much more elementary nature than it is in its final form. It has seemed best, however, to leave these parts as written in order that the work may be of interest to a wider range of readers than it would be were it restricted to a uniform style of treatment. The figures illustrating the venation of the wings of in¬ sects have been drawn with great care under the writer’s direction by Mr. E. P. Felt and Mr. R. H. Pettit. About one half of those in the chapter on Lepidoptera were drawn by Mr. Felt ; the others in this chapter and those in the chapters on Diptera and Hymenoptera were drawn by Mr. Pettit. I wish also to acknowledge the help of my Assistant Mr. A. D. MacGillivray, to whom I am indebted for much aid in bibliographical researches and in many other ways; also* that of Dr. A. C. White of the Cornell University Library, who has generously given much time to determining the etymologies of many of the more obscure words the pro¬ nunciations of which are indicated in the text. PREFACE . Vll To the authorities of Cornell University the authors of this book are under deep obligation for aid and encourage¬ ment. The preparation of the work would not have been possible but for the liberal grants which they have made for the purchase of specimens and books. John Henry Comstock. Entomological Laboratory, Cornell University, December, 1894. f LA T-Lrv I f A ... M J 5 f U V M t Lfl G u M lib CONTENTS. CHAPTER PAGE I. Zoological Classification and Zoological Nomenclature... i II. Insects and their Near Relatives : Branch Arthropoda ; Class Crustacea, Crabs, Lobsters, Crayfish, and Others; Class Arachnida, Spiders, Scorpions, Mites, and Others; and Class Myriapoda, Centipedes and Millipedes . 9 III. Class Hexapoda or Insects: Characteristics of the Class; Metamorphoses of Insects ; External Anatomy of In¬ sects; Internal Anatomy of Insects; Table for Deter¬ mining the Orders of Insects; List of the Orders of Insects . 48 IV. Order Thysanura, Bristle-tails, Spring-tails, Fish- moths, and Others . 82 V. Order Ephemerida, May-flies . 86 VI. Order Odonata, Dragon-flies . 89 VII. Order Plecoptera, Stone-flies . 93 VIII. Order ISOPTERA, Termites or White-ants . 95 IX. Order CORRODENTIA, Book-lice and Others . 98 X. Order Mallophaga, Bird-lice . 100 XI. Order Dermaptera Earwigs . 102 XII. Order Orthoptera, Cockroaches, Crickets, Grasshop¬ pers, Locusts, and Others . 104 XIII. Order Physopoda, Thrips . 119 XIV. Order Hemiptera, Bugs, Plant-lice, Bark-lice, and Others . 121 XV. Order Neuroptera, the Dobson and Others . 175 XVI. Order Mecapter A, Scorpion-flies . 184 XVII. Order Trichoptera. Caddice-flies . 186 XVIII. Order Lepidoptera, Moths, Skippers, and Butterflies.. 191 XIX. Order Diptera, Flies . 413 XX. Order Siphonaptera, Fleas . 49° XXL Order Coleoptera, Beetles . 494 XXII. Order Hymenoptera Bees, Wasps, Ants, and Others.. 599 Index and Glossary . — 679 ix EXPLANATION OF PLATES, PLATE I. (Frontispiece.) FIGURE 1. The Carpet Beetle . 2. The Twelve-spotted Diabrotica . 3. The Adalia bipunctata . 4. The Silver-spotted Skipper . 5. The American Copper . 6. The Red Admiral . . . 7. The Painted Beauty . PLATE II. (Page 68.) THE INTERNAL ANATOMY OF A CATERPILLAR. PLATE III. (Page 70.) THE INTERNAL ANATOMY OF A COCKROACH. PLATE IV. (Page 343.) PSEUDOHAZIS HERA. PLATE V. (Page 353.) FIGURE 1. The Luna Moth . . 2. The Crinkled Flannel-moth . . PLATE VI. (Page 389.) I. The Spring Azure . s. The Green Comma . 3. The Hop-merchant . 4. The Banded Elfin . 5. The Mourning-cloak . 6. The Olive Hair-streak . 7. The Spring Azure . . 8. The Violet Tip . . . . . PAGE 539 577 535 370 390 401 401 PAGE 353 218 391 404 405 393 403 393 39i 405 9 ■ i U*Vr'H*K. M*i3F \*n MELBOURliii A MANUAL FOR THE STUDY OF INSECTS. CHAPTER I. ZOOLOGICAL CLASSIFICATION AND NOMENCLATURE. I. Zoological Classification. (For advanced students .) In order that the myriad forms of animals may be studied with facility some system of classification is necessary. And now that we have learned that there exists a blood-relationship between the differ¬ ent kinds of animals, that system which most clearly expresses this relationship is doubtless the best. This system is termed the Natural Classification . It is now generally believed that long ago, in early geological times, there existed on the earth only very simple animals and plants; and that from these simple beginnings more and more complex forms have been developed. This growth in complexity has taken place in different descendants of these simple primitive beings in very differ¬ ent ways. Thus while it is probable that the first animals lived in water, and very many still do so, others have become adapted to life on the land, and in still others organs have been developed by which they can fly through the air. And under each of these conditions we find a great diversity of norms, each fitted for some special mode ol tife. 2 2 THE STUDY OF INSECTS, The diversity of forms of animal life is much greater than is com monly supposed. A competent authority has estimated that there are now living on the earth more than one million species of animals. And these are merely the surviving descendants of immense series of beings that have existed in past geological times, the remaining tips of a great genealogical tree, of which many twigs and branches have perished. The common figurative use of the word tree in this connection expresses well the convergence of the lines of descent toward the common ancestor from which existing forms have descended. But in one respect it may be misleading. If an ordinary tree be ex¬ amined, the tip of one branch will closely resemble that of any other branch of the same tree. But in this figurative genealogical tree we must imagine a very different state of affairs. Here the law of growth is constant change; each branch grows in its own individual way; and each twig of each branch bears fruit peculiar to itself. The changes, however, are gradual ; and thus the tips of closely-con¬ nected twigs will be similar though not identical ; while the tips of two branches that separated early in the growth of the tree will be very different. It is the effort of the systematist, one who studies the classification of animals and plants, to work out the relations which exist between the various tips of the genealogical tree. This study when carried to its fullest extent includes not only the study of existing forms of life, but also the study of those that have perished, the trunk-forms from which existing forms have descended. This, however, is a very difficult matter; and as yet only the beginnings of the Natural Classification have been made. See pp. 199 to 204. If we accept this theory of descent, now almost universally ac¬ cepted by naturalists, it is evident that when we take into account all the forms of life that have existed we cannot classify animals into well-marked groups; for as the modification in form is gradual, series of connecting links have existed between any two forms that might be selected. But practically the student that confines his attention to the study of living forms can classify these forms into more or less well- marked groups, for many of the connecting links have perished; in fact, the groups of living animals and plants are so distinct that it is only in recent years that naturalists have come to understand the blood-relationship referred to above. We find that the Animal and Vegetable Kingdoms are made up oi a vast assemblage of individuals, each the offspring of parents similar ZOOLOGICAL CLASSIFICATION. 3 to itself, and each in turn producing similar offspring. Although the Cffspring is never exactly like either parent, the degree of variation in a single generation is slight. And thus we find that there exist large numbers of individuals which very closely resemble each other. Such collection of individuals is termed in popular language a kind, in scientific language a species . Thus the kind of pine trees known as pitch-pine is a species; and scrub-pine, still another. In the same Way the name sparrow-hawk indicates a kind or species of hawk; and pigeon-hawk, another species. Roughly speaking, a species is a collection of individuals which resemble each other as closely as the offspring of a single parent. For example, if any two pitch-pines be studied, nothing will be found to indicate that they may not have sprung from seeds grown upon the same tree. On the other hand, if a pitch-pine and a white-pine be carefully compared, they will be found so different that no competent observer would believe that they had a common parent. Unfortunately this mode of defining the limits of a species cannot be depended upon. Many instances are known where forms of animals or plants living in widely-separated regions differ so greatly that they have been considered distinct species until more extended collections in the intermediate regions have brought to light series of intermediate forms, which connect the two so-called species so closely that it is impossible to say where the one ends and the other begins. The only definite way of determining whether two forms are specifically distinct is to determine whether they naturally interbreed or not. We find among wild animals a sort of race prejudice which keeps the members of different species from pairing, although they may do so when demoralized by domestication. Except in the case of very-closely-allied species, the pairing of individuals of different species results in no offspring or in the production of sterile offspring. This grouping of individuals into species not only facilitates our study of Natural History, but expresses certain important facts of inheritance and reproduction. A second and somewhat similar step is made by grouping species into genera. We find that there exist groups of closely-allied species, species that resemble each other in all of the more important characters, and differ among themselves only in what are known as the specific characters. Such a group of species is termed a genus. Thus all the different species of pine taken together constitute the genus pine, or Pinus, as it is termed by botanists. There are many species or oak, 4 THE STUDY OF INSECTS. as red-oak, live-oak, and water-oak. All of the species of oak taken together constitute the genus Querctis of botanists. Several species of hawks and falcons are classed together by zoologists as the genus Falco. The genera in turn are grouped into families. Thus the pines, the spruces, and the larches resemble each other quite closely, and are classed together as the Pine Family (Abietinece) ; the falcons, hawks, kites, and eagles are classed together as the Falcon Family (Falconidce). Closely-allied families are grouped together to form orders . The Pine Family, the Cypress Family, and the Yew Family comprise the Order Coniferce , or cone-bearing plants, of botanists. The Owl Fam¬ ily (< Strigida> ). the Falcon Family (Falconidce), and the Vulture Family ( VuUuridce ) constitute the Order Rap lores, or Birds of Prey. Closely-allied orders are grouped together to form classes. Thus all the orders of birds taken together constitute the Class Aves or Birds. The classes are grouped into branches , which are the principal divisions of the Animal Kingdom.* In studying the different forms of animals it is found that there are several distinct types of structure. Some animals are built upon one plan or structure, and others on other plans. All animals built on the same plan are said to belong to the same Branch. Thus the back-boned animals comprise the Bra?ich Vertebrata; the clams, oysters, snails, cuttle fish, and certain other allied forms comprise the Branch Mollusca ; and the insects, spiders, centipedes, lobsters, and their near relatives comprise the Branch Arthropoda . All the branches of animals taken together constitute the Animal Kingdom. It is not possible to lay down rules by which these different groups of animals can be limited. For, as has been shown in our discussion of species, all have been connected in past time by intermediate forms But notwithstanding this, each of the terms given above (Branch, Class, Order, Family, Genus, and Species) expresses a pretty definite conception, which the student will learn to comprehend by practice in classifying animals. But the sequence in rank of these groups should be learned at the outset. Beginning with the most compre¬ hensive it is as follows : * The principal divisions of the Vegetable Kingdom are not termed Branches ; hence we will not make further use of botanical illustrations in this connection. ZOOLOGICAL NOMENCLATURE. 5 Animal Kingdom. Branch or Subkingdom. Class. Order. Family. Genus. Species. Individual. It is sometime desirable to indicate other groups than those named above. Thus a family may be divided into subfamilies, or an order into suborders. And occasionally an even more minute division is made. Thus several closely-allied families may be grouped together as a superfamily, a group of lower rank than a suborder. The follow¬ ing table includes all the grades of groups now commonly employed : Kingdom. Branch or Subkingdom. Class. Subclass. Superorder. Order. Suborder. Superfamily. Family. Subfamily. Genus. Subgenus. Species. Subspecies. Variety. Individual. V I. Zoological Nomenclature. (For advanced students.') At the beginning of his studies of Natural History the student is met with what is to him a new and strange set of names. These names are often long. In form they belong to a dead language, with which, in these days, even many educated people are unfamiliar. It is not strange that we often hear complaint respecting the difficulty of this nomenclature. s THE STUDY OF INSECTS . A little study of the matter, however, is sufficient to show the necessity for scientific names. The common names of animals will not answer our purpose ; for the same name is often applied to widely different animals in different localities, while a single species of animal is known by totally different names in different sections of the country. In order that information respecting animals may be recorded so that there need not be any doubt regarding the animal to which refer¬ ence is made, it is necessary that each species or group of species should have a distinct name by which it shall be known by naturalists in all parts of the world. Therefore, to each branch, class, order, family, genus, and species which has been described there has been given a special name, by which it is known, and which pertains to this group alone. As this nomenclature is used by all naturalists of whatever nation¬ ality, it is necessary that the names should be in a language which can be understood by all. As Latin was the language in which most scientific books were written at the time this nomenclature was estab¬ lished, that language was chosen as the universal language of science; and the rule has been adopted that all names of animals and plants shall be Latin, or Latin in form. The name of a species consists of two words — the name of the genus to which the species belongs, followed by an adjective indicat¬ ing the particular species ; for in Latin an adjective follows the noun which it qualifies, instead of preceding it as in English. Thus the scientific name of the Pigeon-hawk is Falco columbarius; that of the Sparrow-hawk is Falco sparverius ; and that of the Prairie-falcon is Falco mexicanus . In the case of many species we find well-marked subspecies or geographical races which it is desirable to distinguish by name. Thus the Pigeon-hawk occurs over the whole of North America. But we find that those that live in the northwest coast region extending from California to Sitka, constitute a distinct geographical race known as the Black Merlin. As the Black Merlin and the typical Pigeon-hawk intergrade, they constitute a single species, which is known as Falco columbarius. To the Black Merlin has been applied the subspecific name suckleyi . When, therefore, it is desired to refer to the Black Merlin as distinguished from the typical Pigeon-hawk the term Falco columbarius suckleyi is used. If reference is to be made to the typical Pigeon-hawk as distinguished from the Black Merlin, it is designated as Falco columbarius columbarius. In writing long names like those given above they are frequently ZOOLOGICAL NOMENCLATURE . 7 abbreviated if the context is such that the abbreviations will be read¬ ily understood. Thus the name of the Black Merlin may be written Fa/co c. suckleyi or F. c. suckleyi . Subspecific names are used by entomologists not only to distinguish geographical races, but also to distinguish the different forms of dimorphic and polymorphic species. A good illustration is afforded by a certain species of Swallow-tail Butterfly common in the Atlantic States. This species exists under two distinct forms; one of these is yellow marked with black, and has long been known as Jasoniades turnus ; the other is almost entirely black, and has been known as Jasoniades glaucus. At first it was supposed that these were different species ; but in recent years the two forms have been bred from eggs laid by the same female. It is thus evident that the two forms repre¬ sent a single species. And as the form glaucus was first described its name is given to the species, which is now known as Jasoniades glaucus . This name Jasoniades glaucus is used when reference is made to the species as a whole. But if one wishes to refer to the black form alone, it is distinguished as Jasoniades glaucus glaucus ; while the yellow form is distinguished as Jasoniades glaucus turnus . In the illustrations just given the dimorphism occurs in the same generation. But many instances are known where the dimorphism is seasonal. Thus in the case of certain insects which pass through two or more generations in the course of a year, the different generations, or some of them, differ markedly in form or coloring from the others. These differences in many cases are so great that the different genera¬ tions of the same species were believed to be distinct species till they were bred from each other. It is therefore often desirable to distin¬ guish these different forms by subspecifk names. Thus Iphiclides ajax is a species of Swallow-tail Butterfly which exists under three distinct seasonal forms: an early spring form, I. ajax marcellus ; a late spring form,/, ajax telavionides / and a summer form, /. ajax ajax. The name of a genus or of a subgenus is always a single word, and should be a noun in the singular number and nominative case. The names of all groups of genera (i.e., families, orders, classes, and branches) consist each of a single word , and this word should be a plural noun in the nominative case. The following practices regarding the forms of zoological names are now almost universally followed : The names of all groups in zoology, from kingdom to subgenus inclusive, are written and printed with a capital initial letter. 8 THE STUDY OF INSECTS. Specific and subspecific names are written and printed with a small initial letter. Thus in writing the name of a species the generic name is capitalized, the specific name not ; eg., Iphiclides ajax. The names of families end in idee ; the names of subfamilies, in ince. It will aid the student greatly in the pronunciation of family and subfamily names to know that the / of -idee in family names is short, and consequently the accent falls on the syllable preceding this letter; while the i of -ince of subfamily names is long, and is conse¬ quently accented.* Numerous examples are given in the following pages. * This in accordance with the rule of Latin grammar that in words of more than two syllables the penult if long is accented; but if the penult is short the accent falls on the antepenult. CHAPTER II. INSECTS AND THEIR NEAR RELATIVES. Branch ARTHROPODA (Ar-throp'o-da). The Arthropods ( Ar'thro-pods ). If an insect, a spider, a scorpion, a centipede, or a lobster be examined, the body will bo found to be composed of a series of more or less similar rings or seg¬ ments joined together; and some of these segments will be found to bear jointed legs (Fig. i). All the animals possessing these characteristics are classed together as the Branch Arthropoda. A similar segmented form of the body is found among worms; but these are dis¬ tinguished from the Arthropods by the absence of legs. It should be remembered that many animals commonly called worms, as the tomato-worm, apple-worm, etc., ar& not true worms, but are the larvae of in¬ sects (Fig. 2). The angle-w'orm is the most familiar example of a true worm. The Branch Arthropoda is the largest of the branches of the Animal Kingdom, including many more knov-n species than ail the other branches taken together. Our common representatives are distributed among four classes: these are the Crustacea, the Arachnida, the Myriapoda, and the Hexapoda. The 9 IO THE STUDY OF INSECTS . first three classes are briefly discussed in this chapter; the fourth comprises the Insects, and is the subject of the remaining parts of this book. Fig, 2. — A larva of an insect. The following table will enable the student to distin¬ guish the classes of the Arthropoda.* TABLE OF CLASSES OF THE ARTIIROPODA. A. With two pairs of antennae and at least five pairs of legs. Aquatic animals breathing by gills, p. 1 1 . . . Crustacea. AA. With one pair of antennae or with none. Air-breathing ani¬ mals. The number of legs varies from six to many. * The following is the method of using the analytical tables given in this book: Read carefully the statement of characteristics given opposite A and AA respectively, and by examining the animal to be classified determine which is true of this animal. This will indicate in which division of the table the name of the group to which the animal belongs is to be looked for. If this division. of the tablets subdivided, pass to B and BB (also to BBB if it occurs) in this division and determine in a like manner under which the animal belongs. Continue in this way, passing to the letters C, D, E, etc., in regular order till the name of the group is reached. Then turn to the page indicated and read the description or the group given there, comparing the specimens with the description. It should be borne in mind that an analyt¬ ical table is merely an aid to the determination of groups. As the groups that we recognize are not always sharply limited in nature, we cannot expect to be able in every case to find characters that will serve to distinctly separate them in a table. Therefore when a student has determined by the aid of a key to what group a species seems to belong, he should verify this determi¬ nation by a study of the characters of that group given in the detailed dis¬ cussion of it. INSEC'TS AND THEIR NEAR RELATIVES, . II B. Without antennas and with four pairs of legs, although the maxillary palpi are often leg-like in form, making the animal appear to have five pairs of legs. p. 12 . Arachnida. BB. With antennae. C. With more than three pairs of legs; and without wings, p. 45 . Myriapoda. CC. With only three pairs of legs, and usually with wings in the adult state, p.48 . Hexapoda„ Class Crustacea (Crus-ta'ce-a). The Crustaceans ( Crus-ta’ ce-ans ). The members of this class are aquatic Artliropoda, which breathe by true gills. They have two pairs of ante nncp and at least five pairs of legs . The most familiar illustrations of the Crustacea are thf* Cray-fishes, the Lobsters, the Shrimps, and the Crabs. Cray-fishes (Fig. 3) abound in our brooks, and are often improperly called Crabs. The Lobsters, the Shrimps, and the true Crabs live in salt water. The Crustaceans are distinguished from all oth¬ er Arthropods by their mode of respiration, being the only ones that breathe by true gills. Many in¬ sects live in water, and are furnished with gill-like . , . Fig. 3 —A Cray-fish, organs; but these are tracheal gills, organs which differ essentially in structure from true gills, as described later, in the chapter on Anat¬ omy of Insects. The Crustacea also differ from other Arthropoda in having two pairs of antennae; and from all 12 THE STUDY OF INSECTS. Fig. 4.— Crustacea : a . Cypris; 6 Cyclops; c, Daphnia. except the Myriapoda in having many (more than four) pairs of legs. The illustrations named above are the more conspicuous members of the class ; but many other smaller forms abound both in the sea and in fresh water. Some of the more minute fresh-water forms are almost sure to occur in any fresh¬ water aquarium. In Figure 4 are represented three of these, greatly enlarged. Among the Crustacea that live in damp places on the Sow-bugs, Oniscidce (O-nis'ci-dae), are most often1 seen. These frequently occur about water-soaked wood ; and are often mistaken, by students begin¬ ning the study of Entomology, for insects or Myria¬ pods. Figure 5 represents a Sow-bug. On the sea-coast an immense number of forms FsSwlbu£ of Crustacea occur. land Class Arachnida (A-rach'ni-da). Scorpions , Harvestmen , Spiders , Mites , and others . The members of this class are air-breathing Arthropods, in which the head and thorax are grown together , forming a cephalothorax , which have four pairs of legs fitted for zvalk- mg, and which have no feeler-like antenna . The Arachnida abound wherever insects occur, and are often mistaken for insects. But they can be easily distin¬ guished by the characters given above, even in those cases where an exception occurs to some one of them. The more important of the exceptions are the following: In the Sol- pugida the head is distinct from the thorax ; as a rule the young of mites have only six legs, but a fourth pair are added during growth ; and in the gall mites ( Phytoptus ) there are only four legs. In the Arachnida we find only simple eyes. The cephalothorax (ceph-a-lo-tho'rax) bears six pairs of INSECTS AND THEIR NEAR RELATIVES . 13 Fig. 6. — Lower side of cephalothorax of a spider : tnd, man¬ dible ; tttx, maxilla ; us ; /, lower sternum. dible: ; A palp* lip ; sy s appendages — two pairs of jaws, and four pairs of legs. The first pair of jaws are the mandibles (man'di-bles), the second, the maxillce (max-il'lse). The mandibles (Fig. 6, md) lie in front of and above the mouth, and consist each of two or three segments. The\ serve for seizing prey, and often also for killing it. In many books they are termed the chelicerce (che-lic'e-rae). The maxillce (Fig. 6, nix') lie just behind the mandibles, one on each side of the mouth. Each maxilla bears a large feeler or palpus (Fig. 6,/). These palpi vary greatly in form ; frequently they resemble legs ; hence many Arachnida appear to have five pairs of legs. The palpi are often so largely developed that each maxilla ap¬ pears to be merely the first segment of its leg-like palpus. These appendages are often called the pedipalpi (ped-i-pal'pi). But as the name Pedipalpi is applied to one of the or¬ ders of the Arachnida, we will call these ap¬ pendages the palpi. The legs of Arachnida consist typically of seven parts (Fig. 7), which are named, begin¬ ning with the one next to the body, as fol¬ lows : r, coxa (cox'a) ; 2, trochanter (tro-chan'- ter) ; 3, femur (fe'mur); 4, patella (pa-tel'la); 5, tibia (tib'i-a) ; 6, metatarsus (met-a-tar'sus) ; and 7, tarsus (tar'sus). The tarsus may be composed of several segments, and is usually furnished with claws. Two forms of breathing organs are found in this class : one, tracheae, resembling the tracheae of insects, described in the chapter on the anatomy of insects ; and the other, tracheal lungs or lung sacs, which consist of many leaf-like plates enclosed in a sac. Both forms open by paired spira¬ cles, which are usually situated on the lower side of some of the abdominal segments. 14 THE STUDY OF INSECTS . Very great differences exist in the several orders of the Arachnida in respect to the division of the body into seg¬ ments. In arranging the orders in a series, we place first those in which the segments of the body are most distinctly indicated, while those which seem to depart more widely from the segmented type characteristic of the Arthropoda are placed later. The class Arachnida includes seven orders ; these are designated as follows : The Scorpions, Order SCORPIONIDA (p. 15). The Jointed Spiders, Order SOLPUGIDA (p. 16). The Pseudoscorpions, Order PSEUDOSCORPIONES (p. 17). The Whip-scorpions, Order PEDIPALPI (p. 17). The Harvestmen, Order Phalangidea (p. 19). The Spiders, Order Araneida (p. 20). The Mites, Order Ac ARINA (p. 42). TABLE OF THE ORDERS OF THE ARACHNIDA. A Abdomen distinctly segmented. B. Abdomen with a tail-like prolongation. C. Tail stout and armed with a sting at the end ; first pair of legs not greatly elongated; a pair of comb-like appendages on the lower side of the second abdominal segment in the adult. ( Scorpions .) p. 15 . . . SCORPIONIDA. CC. Tail slender, whip-lash-like, without sting; first pair of legs much longer than the others; without comb-like appendages on abdomen. ( Whip-scorpions .) ( Thdyphonidcs.) p. 17. Pedipalpi. BB. Abdomen without a tail-like prolongation. C. Palpi with pincer-like claws. ( Pseudoscorpio?is .) p. 17. PSEUDOSCORPIONES. CC. Palpi without pincer-like claws. D. Abdomen joined to the thorax by a slender stalk; front legs greatly elongated and with whip-lash-like tarsi. ( Whip- scorpions .) ( Phrynidce. ) p. 17 . PEDIPALPI. DD. Abdomen broadly joined to the thorax. E. Legs usually very long and slender; thorax not dis¬ tinctly divided into three segments. (Harvestmen.) p. 19. Phalangidea. EE. Legs moderately long; head distinct from thorax ; thorax distinctly divided into three segments, p. 16. Solpugida. INSECTS AND THEIR NEAR RELATIVES . 15 AA. Abdomen unsegmented. B. Abdomen joined to the cephalothorax by a short, narrow stalk. (Spiders.) p. 20 . Araneida. EB. Abdomen fused with the cephalothorax. (Mites.) p. 42. Acarina. Order SCORPIONIDA (Scor-pi-on'i-da). The Scorpions . With the scorpions (Fig. 8), the body is divided into a compact, unsegmented cephalothorax, and a long, segmented abdomen. The abdomen is divided into two portions : a broad pre-abdo¬ men, consisting of seven segments ; and a slenderer tail-like division, the post-abdomen, consisting of five seg¬ ments. At the end of the post-abdo¬ men there is a large poison-sting, which appears like a segment. The mandibles and the palpi are provided with pincers. As the palpi are very large, with stout pincers, they resem¬ ble in a striking manner the great claws of lobsters. The cephalothorax bears from three to six pairs of eyes. Scor¬ pions breathe by means of lung sacs, of which there are four pairs, opening on the lower side of the third to the sixth abdominal segments. Full-grown scorpions possess a pair ot comb-like organs on the lower side of the second abdominal segment. The function of these organs is not yet known. The sexes of scorpions differ in that the male has broader pincers and a longer post-abdomen. Scorpions do not lay eggs, the young being developed within the mother. After the birth of the young, the mother apparently shows great regard for them, carrying them about with her for i6 THE STUDY OF INSECTS. some time, attached by their pincers to all portions of her body. Scorpions live in warm countries. They are common in the southern portion of the United States, but are not found in the North. They are nocturnal, remaining concealed dur¬ ing the day, but leaving their hiding-places at dusk. When they run the post-abdomen is bent upwards over the back. They feed upon spiders and large insects, which they seize with the large pincers of their palpi, and sting to death with their caudal poison sting. The sting of a scorpion rarely if ever proves fatal to man, although the larger species, which occur in the Tropics, pro¬ duce serious wounds. Nearly twenty species are known from North America. Order SOLPUGIDA (Sol-pu'gi-da). The Jointed Spiders. The members of this order differ from all other Arach- nida in having the head separate from the thorax, and in having the thorax composed of three distinct segments, as with insects. The mandibles are very large, and are furnished with strong pincers. The palpi are shaped like the legs, and are said to be used in locomotion. The first of the four pairs of true legs, like the palpi, are not furnished with claws, and are used as palpi. There are only two eyes. Respi¬ ration is effected by means of „ . tracheae, which open through three Fig. 9.— A Jomted-spider, Datames # , 1 0 diiatata. (After Putnam.) pairs of spiracles, situated in the first thoracic and the second and third abdominal segments. Only a few species of Solpugida occur in the United States, and specimens of these are rarely found. So far INSECTS AND THEIR NEAR RELA TIVES. IJ as is known, our species are nocturnal, remaining con- cealed during the day. They prey upon small insects, and are believed to be harmless. Figure 9 will serve to show the appearance of these curious animals. The popular name, jointed-spiders, is suggested by the segmented con¬ dition of the abdomen. Order PSEUDOSCORPIONES (Pseu-do-scor-pi'o-nes.) The Pseudoscorpions . The pseudoscorpions (Fig. 10) are small Arachnida, which resemble scorpions in the form of their body, except that the hinder part of the abdomen is not nar¬ row, as is the post-abdomen of scorpions, and they have no caudal poison-sting. The abdo¬ men is broad, flat, and composed of eleven segments, or in some cases of only ten. The pseudoscorpions possess only one or two pairs of eyes, and in some, eyes are want¬ ing. They breathe by means of tracheae, ’dawTorpionf*11* which open through two pairs of spiracles on the lower side of the second and third abdominal segments. These little scorpion-like creatures live under stones, be¬ neath the bark of trees, in moss, and in the dwellings of man, between the leaves of books, etc. They run rapidly, side- wise and backwards ; and feed on mites and small insects. They are often found attached to insects, especially to flies; but they probably do not feed on these large insects, but merely use them as means of rapid locomotion. The pseudoscorpions occur in the Northern States as well in the South. Order Pedipalpi (Ped-i-pal'pi). The Whip-scorpions . These strange creatures are found only in the extreme southern part of our country, being tropical animals. In 3 IS THE STUDY OF INSECTS. their general form they have some resemblance to scor¬ pions. They can be easily distinguished by the form of the front legs, which are greatly elongated, and have the tarsi broken up into many small segments; this gives these legs a more or less whip-lash-like appearance. In one family the abdomen also bears a whip-lash-like appendage. The mandibles are furnished with claws; the palpi are very large and armed with strong spines, and the abdomen is distinctly separated from the thorax. The order includes two families, both of which are represented in the United States. Family Ti-ielyphonidje (Thel-y-phon'i-das). The Tail Whip-scorpions . This family is represented in the United States by only a single species, the Giant Whip - scorpion, ThelypJionus giganteus (T h e-ly p h 'o-n us gi-gan - te'us). This species measures when full grown from four to five inches in length. Figure 1 1 represents one less than natural size. These whip-scorpions are great¬ ly feared on account of theirsupposed venomous powers, but it is prob¬ able that there is no foundation for this fear. Although it has been stated often that their bites are poisonous, we Fig. ii .—Theiypkonus giganteus, can find no direct evi- INSECTS AND THEIR NEAR RELA TIVES. 19 dence that it is so. They destroy their prey by crushing it with their palpi. Family Phrynid.® (Phryn'i-dse). The Tailless Whip-scorpions. This family is represented in our fauna by the genus Phrynus (Phry'nus), the members of which are smaller than the Giant Whip-scorpion. In this family the front legs are even more whip-lash-like than in the preceding family; the whole body is relatively shorter and broader; the abdomen is joined to the thorax by a slender stalk, and the tail-like appendage is lacking. Order PHALANGIDEA (Phal-an-gid'e-a). The Harvestmen , or Daddy Long Legs. The Harvestmen are very common in most parts of the United States. They are well known to children in this country under the name Daddy Long Legs, but as this name is also sometimes applied to Crane-flies, Harvestmen jg preferable. In some sections of the country the Har¬ vestmen arc known as Grandfather Graybeards. Most Harvestmen can be recognized by their very long and slender legs (Fig. 12), although some species have comparatively short ones. The cephalothorax is indistinctly if at all segmented. The abdomen is short, broad, consists 20 THE STUD Y OF INSECTS. of six segments, and is without a tail-like appendage; it is broadly joined to the cephalothorax. The eyes of the Harvestmen are two in number, and are situated on a prominent tubercle near the middle of the cephalothorax. The mandibles are pincer-like. The maxillae are large, and so opposed as to act as jaws ; their palpi are four-jointed, and are small compared with the palpi of the preceding orders; they resemble in form and func¬ tion the palpi of insects. The members of this order breathe by tracheae, which open by a single pair of spir¬ acles, on the lower side of the body at the junction of the cephalothorax and abdomen. The Harvestmen feed on small insects, especially Aphids, and are perfectly harmless. They are said to devour their prey, chewing it with their maxillae, and swallowing it, y instead of merely sucking out the blood, as do most other £ Arachnida. ^ Cl Although the Harvestmen have stilt-like legs, they do w not raise the body much above the ground when they t. walk, but carry it quite near their feet, with the middle u part of their legs high in the air. They are said to pounce ; upon their prey as does a cat upon a mouse, and seize ^ it with their palpi as if with hands. It is a common practice with children to catch these creatures and say to them, “ Grandfather Graybeard, tell me where the cows are, or Til kill you.” As the poor frightened animal points its legs in all directions in its frantic efforts to escape, it usually earns its freedom ; but too often it is not without the loss of one or more legs. Order Araneida (Ar-a-ne'i-da). The Spiders . The Spiders differ from other Arachnida in having the abdomen unsegmented and joined to the cephalothorax by a short, narrow stalk. The cephalothorax is also un- »|A T* INSECTS AND THEIR NEAR RELA TIVES. 21 segmented ; and the abdomen bears at its end organs for spinning silk (Fig. 13). Fig. 13. — Pence tia viridans. (From the Author’s Report on Cotton Insects.) The mandibles (Fig. 14, md) consist of two segments, a strong basal one and a claw-shaped terminal one, at the tip of which a poison gland opens (Fig. 15). It is by means of these organs that spiders kill their prey. The palpi are leg¬ like in form, but differ greatly according to sex. In the female the last segment of the palpus resembles a foot of the spider, and is usually armed with a well-developed curved claw. But in the male the corre¬ sponding segment is more or less enlarged, and very complicated in structure (Fig. 16). The greater number of spiders have four pairs of eyes (Fig. 17), but there may be Fig. 14.— Lower side of cephalothorax of a spider ; md, man¬ dible; mxy maxilla; A palpus ; /, lower lip; Sy sternum. Fig. 15.— Tip of claw of mandible of spider. Fig. t6. — Maxilla and palpus of male house- spider. Fig. 17. — Head of epider, showing eyes and mandi¬ bles. 22 THE STUDY OF INSECTS . only one, two, or three pairs ; and certain cave spiders are blind. Spiders breathe by means of lung-sacs, of which there are one or two pairs ; and some have tracheae also. The lung-sacs open on the lower side of the abdomen near its base, and between them is the opening of the reproductive organs. The tracheae open through a single spiracle near the hind end of the body, just in front of the spinning organs. The spinning organs, which are situated near the end of the abdomen, consist of two or three pairs of spinnerets. These appendages (Fig. 18) are more or less finger-like in form, and some¬ times jointed. Upon the end of each spinneret there are many small tubes, the spinning tubes, from which the silk is spun (Fig. 19). Some spiders have as many as one hundred and fifty or two hundred of these spinning-tubes on each spinneret. The silk is in a fluid state while it is within the body, but it hardens as soon as it comes in contact with the air. In addition to the many small spinning tubes, there are a few larger ones, termed spigots. The ordinary thread is spun from two or four of these. The small spinning tubes are used in making attachment disks for fast¬ ening threads in place, in making a swathing band for enveloping prey, and, sometimes, in making a fig. x9. broad, wavy band across the center of a web. We *$£££* have observed a spider seize a large grasshopper greatly which was entangled in its web, and, rolling it over cnlar^ed* two or three times, completely envelop it in a sheet of silk spun from its spread-apart spinnerets. In the construction of their web some spiders make use of two kinds of silk. One of these is dry and inelastic ; the other, viscid and elastic. This fact can be easily seen by examining an orb-web. If the spiral line which forms Fig. t8. — End of abdomen of spider, showing six spinner¬ ets spread apart: in front of these is the spiracle, and be¬ hind them the open. ngot the alimentary canal. INSECTS AND THEIR NEAR RELATIVES. 23 the greater part of the web be touched, it will adhere to the finger, and will stretch, when the finger is withdrawn, to several times the original length. But if one of the radiat¬ ing lines or a portion of the outer framework be touched, it will neither adhere to the finger nor be stretched. If the spiral line be examined with a lens, it will be found to bear numerous bead-like masses of viscid matter (Fig. 20); this explains its adhesiveness. It is supposed that the two kinds of silk are spun from different spinnerets, and that the viscid silk comes from the front pair. When this silk is first spun the viscid matter forms a continuous layer of liquid on the outside of it. But very soon this layer breaks up into the bead-like masses — in a way similar to that in which the moisture on a clothes-line in a foggy day collects into drops. Spiders of the two families Dictynidce and Uloboridce have spinning organs differing from those of all other Fig. 20.— Viscid silk Fig. 21.— Spinnerets of Fig. 22.— Last two segments from an orb web. a Dictynid spider. of hind leg of spider, show- The middle pair of ing calamistrum. spinnerets are con¬ cealed by the first pair, r, cribellum. spiders. They have in front of the usual spinnerets an additional organ, which is named the cribellum (cri:berium) (Fig. 21). This bears spinning-tubes like the other spinner¬ ets, but these tubes are much finer. These spiders have also on the metatarsus of the hind legs one or two rows of curved spines : this organ is the calamistrum (cal-a-mis'trum) (Fig. 22). By means of the calamistrum these spiders comb from the cribellum a band of loose threads, which forms a part of their webs. 24 THE STUD Y OF INSECTS. Spiders make use of silk in the construction of their webs or snares, in the building of tubes or tents within which they live, in the formation of egg-sacs, and in loco¬ motion. Fig. 23 represents the large egg-sac of one of the orb- weavers. This is made in the autumn, and contains at that season a large number of eggs — five hun¬ dred or more. These eggs hatch early in the winter; but no spiders emerge from the egg-sac until the following spring. If egg-sacs of this kind be opened at differ¬ ent times during the winter, as was done by Dr. Wilder, the spiders will be found to increase in size but diminish in num¬ ber as the season advances. In fact, a strange tragedy goes on within these egg-sacs: the stronger spiders calmly devour their weaker brothers, and in the spring those which survive emerge sufficiently nourished to fight their bat¬ tles in the outside world. The egg-sacs of the different species of spiders vary Fig. 23. — Egg-sac of A rgiope riparia, (From Wilder.) Fig. 24.— Egg-sac of Nephila plum! pcs (From Wilder.) greatly in form. In some, as in that figured above, the outer covering is very dense, while in others the outer part con- INSECTS AND THEIR NEAR RELATIVES. 25 sists of loose flossy silk (Fig. 24). One of the most common kinds is very flat, silvery in color, and is firmly attached to stones lying upon the ground (Fig. 25). Every on~ knows that a spider wishing to descend to some place beneath it simply fastens a line to the object which it is upon and then drops boldly off, regulat- Fic 25. _Egff.sac of a ing the rate of its descent by spinning Drassid* the line rapidly or slowly; when the spider wishes to return, it has only to climb up the same line. Frequently spiders pass from point to point in a hori¬ zontal direction by means of silken bridges. These are formed in this way : The spider spins out a thread, which is carried off by a current in the air. After a time the thread strikes some object and adheres to it ; then the spider pulls the line tight, and fastens it where it is standing. It then has a bridge, along which it can easily run. But more remarkable than either of these uses of silk for locomotion is the fact that many spiders are able to travel long distances, hundreds of miles, through the air by means of these silken threads — “sailing mid the golden air In skiffs of yielding gossamere.” — ( Hogg .) The Aeronautic Spiders, or Flying Spiders, as they are more commonly called, are frequently very abundant, espe¬ cially in warm antumn days. At such times innumerable threads can be seen streaming from fences, from bushes, and the tips of stalks of grass, or floating through the air. The flying spider climbs to some elevated point, which may be merely the tip of a stalk of grass, and then, standing on the tips of its feet, lifts its body as high as it can, and spins out a thread of silk. This thread is carried up and away by a current of air. When the thread is long enough the force of the air current on it is sufficient to buoy the spider up. It 20 THE STUDY OF INSECTS. then lets go its hold with its feet and sails away. That these spiders travel long distances in this manner has been shown by the fact that they have been seen floating through the air at sea far from land. Representatives of nearly thirty families of spiders have been found in the United States. But some of these fami¬ lies include only rare species, and others arc represented by so few species that we cannot discuss them here. The greater number of our spiders belong to the eleven families described below. The following table will aid the student in separating these families. TABLE FOR SEPARATING THE PRINCIPAL FAMILIES OF SPIDERS. A. Claw of the mandibles moving vertically; four lung-slits present. ( Tarantulas .) p. 27 . Theraphosid^e. AA. Claw of the mandibles moving horizontally; only two lung-slits present, but with a single spiracle or a pair of spiracles also. B. Eyes equal or nearly equal in size, and usually arranged in two rows. C. Feet furnished with two claws (Fig. 28). Spiders which do not spin webs for catching prey. D. Second pair of legs not so long as the fourth pair. E. Maxillae with a concavity or furrow (Fig. 29). Spiders which live on the ground, p. 29 . DRASSIDJE. EE. Maxillae convex (Fig. 32). Spiders which live chiefly in silken tubes on bushes, p. 30 . Clubionid.e. DD. Second pair of legs as long as or longer than the fourth pair. ( The crab-spider si) p. 40 . Thomisid^E. CC. Feet furnished with three claws (Fig. 38). Spiders which spin webs for catching prey. D. The caudal pair of spinnerets very long, and two-jointed. Spiders which make irregular webs with a tube or hiding- place at one side, from which they run on the upper surface of the web, to catch their prey. p. 30 . AgalenidjE. DD. All of the spinnerets short. E. With cribellum and calamistrum. Spiders making webs in which there are curled threads, or double threads. /NSECTS AND THEIR NEAR RELATIVES. 27 F. The side eyes not as far apart as the middle eyes; a considerable space between the eyes and the front edge of the head. Spiders making irregular webs. p. 32. DlCTYNIDiE. FF. The side eyes as far or farther apart than the middle eyes; eyes very close to the front edge of the head. Spiders making regular webs. ( Uloborus .) p. 38. ULOBORIDiE. EE. With neither cribellum nor calamistrum. Spiders mak¬ ing webs in which there are no curled threads. F. Eyes not near the front edge of the head, the space be¬ tween the two being greater than that occupied by the eyes (Fig. 37). Spiders that spin irregular webs, in or near which they live, hanging back downwards, p. 34. Theridiid^e. FF. Eyes near the front edge of the head, the space be¬ tween the two being less than that occupied by the eyes (Fig. 42). Spiders that make regular webs, consisting chiefly of lines radiating from the centre, and a spiral or looped sticky line. p. 35 . Epeirid/E. 3B. The eyes unequal in size and arranged in three or four rows. C. With cribellum and calamistrum. Spiders which make webs. {Hypt totes.) p. 38 . Uloborid;e. CC. With neither cribellum nor calamistrum. Spiders which do not spin webs for catching prey. D. The largest eyes not in the front row. ( Running spiders .) P- 4° . ; . LYCOSIDiE. DD. The largest eyes in the front row. ( Jumping spiders .) p- 42 . AttidjE. Family Theraphosid^E (Ther-a-phos'i-dae). The Tarantulas and the Trap-door Spiders . Those who live in the warmer parts of our country know well the large spiders commonly called Tarantulas. These are the giants among spiders, some of them being the largest known ; but some species of this family are not very large. They are dark-colored, hairy spiders, and can be distinguished from the other families mentioned here by the fact that the 28 THE STUDY OF INSECTS. claw of the mandibles works up and down instead of side- wise. The members of this family do not construct true webs, but they dig long tubes in the earth, which they line with silk, or line their hiding-places in clefts in trees or elsewhere with a layer of silk. They live only in warm countries. One of the best known of the Tarantulas is Eurypelnia hentzii (Eu-ryp'el-ma hentz'i-i). This species occurs in the South and in the Middle West, and is the largest of our spiders (Fig. 26). Several closely allied species are found in California. Fig. 26.— A Tarantula, Eurypelnia hentzii . But the members of this family that have attracted most admiration on account of their habits are the Trap-door Spiders. These dig a tube in the ground, as do many other members of this family ; but this tube is lined with a denser Fig. 27. — Entrance to nest of a trap-door spider. layer of silk, and is provided with a hinged lid, which fits the opening of the tube with wonderful accuracy (Fig. 27). INSECTS AND THEIR NEAR RELATIVES . 29 The spider hides in this nest when not seeking its prey. Some species take the precaution to build a branch to their nest, and to provide this branch with a door. As this door forms a part of one side of the main tube, it is not likely to be observed by any creature which may find its way past the first door of the nest. Several species of Trap-door Spiders occur in the South¬ ern and Southwestern States. Family DRASSIDS (Dras'si-das). The Drassids , or Tube Weavers in part . There are certain dark-colored spiders that spin no web, but wander about at night in search of prey, and hide under leaves and stones during the day-time. Many of them make silken tubes, in which they hide in winter or while moulting or laying eggs. Hence they have been termed Tube Weavers, a name which is also applied to certain other spiders. We will therefore call the members of this family the Drassids (Dras'sids). In this family the body is long, and is usually flattened above. It is carried near the ground in walking. The legs are rather short and stout; the second pair are not longer than the fourth, and the feet are furnished with only two claws (Fig. 28). The eyes are in two nearly straight rows, and the maxillae are concave or fur¬ nished with a furrow (Fig. 29). One of the most Fig. 28.— Foot of a Drassid. Fig. 29. — Maxilla of a Drassid. Fjg. 30. — Drassus saccatus. common species in the East is Drassus saccatus (Dras'sus sac-ca'tus) (Fig. 30). It lives under stones, in a large bag of silk, in which the 30 THE STUDY OF INSECTS . female stays with her egg-sac. In early summer a male and female live together in the nest. Family CLUBIONID/E (Clu-bi-on'i-dae). The Clubtonids, or Tube Weavers in part . There may be found during summer, in flat tubular nests on plants, usually in rolled leaves, spiders that spin no webs to entrap their prey. These spiders very closely re¬ semble the Drassids in structure, but are usually lighter in color, with the legs a little longer and more slender, and the abdomen more nearly cylindrical (Fig. 31). Fig. 3i. — ciubi- Fig. , ..-Maxilla of They are also distinguished by ona canadensis. a Clubiomd. |-Jie form of the maxillae, which are convex (Fig. 32). These spiders belong to the family Clubionidse. As we have no appropriate common name for these spiders, they may be called the Clubionids (Clu-bi- on'ids). During the winter the Clubionids hide under bark or stones, and make tubular nests in these places. Family Agalenid^E (Ag-a-len'i-dae). The Fu fin el-web Weavers. Even the most careful observers seldom realize what an immense number of spider-webs are spun upon the grass in the fields. But occasionally these webs are made visible in the early morning by the dew which has condensed upon them. At such times we may see the grass covered by an almost continuous carpet of silk. The greater number of the webs seen at such times are of the form which we term funnel-webs. They consist of a concave sheet of silk, with a funnel-shaped tube at one side; INSECTS AND THEIR NEAR RELA TIVES. 31 and numerous lines extending in all directions to the sup¬ porting spears of grass (Fig. 33). The tube serves as a hiding-place for the owner of the web; from this retreat the spider runs out on the upper surface of the web to seize any insect that alights upon it. The tubes open below, near the roots of the grass; so that the spider can escape from it if a too formidable insect comes upon the web. The funnel-web weavers (family Agalenidce) are long- legged, brown spiders, in which the head part of thecephalo- thorax is higher than the thoracic part, and distinctly separated from it by grooves or marks at the sides. The eyes are usually in two rows, but in Agalena the middle eyes of 0 . . . , , Fig. 34. — A galena neevia. both rows are much higher than the others. The feet have three claws. The posterior pair 32 THE STUDY OF INSECTS. of spinnerets are two-jointed, and usually longer than the others. The common grass spider, which abounds in all parts of the United States, is Agalena nczvia (Ag-a-le'na nas'vi-a (Fig. 34). Family DlCTYNIDiE (Dic-tyn'i-dae). The Curled-thread Weavers with Irregular Webs. The Dictynids (Dic-tyn' ids). Certain spiders are remarkable for using two kinds of silk in the formation of their webs. Thus, as explained later, the Orb Weavers build the framework of their orbs of dry and inelastic threads, and attach to this framework a thread which is sticky and elastic ; while most spiders which make irregular webs use only one kind of silk. There are, however, certain species of irregular web-weavers which use two kinds of silk. One of these is a plain thread like that spun by other spiders, and the other is a peculiar curled thread or a delicate band of tissue in which there are curled threads. The curled-thread weavers represent two families, one of which makes irregular webs; the other, those which are of definite form. The first of these is the Dictynidcz. The curled -thread or tissue-like band is made in the same way by both families. It is composed of silk spun from a special spinning-organ, situated in front of the ordinary spinnerets, and named the cribellmn (cri-berium) ; and is combed into its peculiar form by means of a comb of stiff hairs, the calamistrum (cal-a-mis'trum), which is borne by the metatarsus of the hind legs (see page 23). In mak¬ ing the curled thread the spider turns one of its hind legs under the abdomen so that the calamistrum is just under the cribellum, and the foot rests on the other hind leg. It then moves its hind legs back and forth rapidly, so that the calamistrum combs out from the spinning-tubes, and at the same time tangles, a band of fine threads. Fig. 36.— W eb of a Dictynid, on a dead branch of Ceanothus, somewhat enlarged. on plants. These webs are especially common among the flowers of Golden-rod and other plants having clusters of INSECTS AND THEIR NEAR RELATIVES. 33 This band of tangled or curled threads is easily seen in the webs of these spiders, being wider than the ordinary threads and white in color. In old webs it becomes conspicuous by the large amount of dust which it collects. Figure 35 shows the appearance of this band when magnified, and the way in which it is attached to the plain threads. Our more common Dictynids make webs of various shapes, on fences, under stones, in holes in rotten logs, and Fig. 35.— Curled thread of Dictynid, larged. a en- 34 THE STUDY OF INSECTS . small flowers (Fig. 36), and exhibit a slight degree ol regularity. Family Theridiid.® (Ther-i-di'i-dae). The Cobiueb Weavers. Many are the kinds of webs spun by different spiders. Some of them, as the orb-webs and the funnel-webs, delight us with their wonderful regularity of form ; while others appear to be a mere shapeless maze of threads. Such are the structures whose presence in the corners of our rooms torment thrifty housewives, and which are disrespectfully termed cobwebs. The cobweb weavers (Family Theridiidce) are small spiders with unusually slim legs. The space between the eyes and the front edge of the head is greater than the Fig. 37. — Face of Fig. 38.— Foot of spider Fig. 39. — Mtmetus house spider. with three claws. interfector. region occupied by the eyes (Fig. 37); the eyes are in two rows ; and the feet are furnished with three claws (Fig. 38), This family includes many species, being in fact the largest of all of the families of spiders. Figure 39 represents a widely distributed species. Although the house spiders are the most familiar mem¬ bers of this family, the greater number of species spin their webs in the fields on bushes. These webs usually consist of a flat or curved sheet, under which the spider hangs back downward. This sheet is supported by threads running in all directions to the neighboring objects. Frequently there is a large number of these supporting threads above the web, which serve the additional purpose of impeding the flight of INSECTS AND THEIR NEAR RELATIVES. 35 insects, and causing them to fall into the web, where they are caught. Some of these spiders do not remain in their webs, but have a nest in a neighboring crack or corner, from which they rush to seize their prey. And sometimes there is a funnel-shaped tube leading to this nest. But these spiders differ from the true funnel-web weavers in running back down¬ wards on the lower side of their web. Family Epeirid^e (E-pei'ri-dae). The Orb Weavers . Few if any of the structures built by lower animals are more wonderful than the nets of orb-weaving spiders, but these beautiful objects are so common that they are often considered hardly worthy of notice. If they occurred only in some remote corner of the earth, every one would read of them with interest. The nets of the different species of orb weavers differ in the details of their structure, but the general plan is quite similar. There is first a framework of supporting lines. The outer part of this framework is irregular, depending upon the position of the objects to which the net is attached; but the more central part is very regular, and consists of a number of lines radiating from the center of the net (Fig. 41). All of these supporting lines are dry and inelastic. But there is spun upon the radiating lines in a very regular manner a thread which is sticky and elastic (Fig. 20, p. 23). Usually this sticky thread is fastened to the radiating lines so as to form a spiral, but a few species make nets in which this thread is looped back and forth. Many of the orb weavers strengthen their nets by spin¬ ning a zigzag ribbon across the center. This ribbon is made by spreading the spinnerets apart so that the minute threads from the spinning tubes do not unite to make a single thread, as is usually the case. Some of the orb weavers live in their nets hanging head S6 THE STUDY OF INSECTS. downwards, usually near the center of the net ; others have a retreat near one edge of the net, in which they hang back Fig. 41. — Partially completed web of Epeira. downwards. While resting in these retreats they keep hold of some of the lines leading from the net, so that they can instantly detect any jar caused by an entrapped insect. When an insect in its flight touches one of the turns of the sticky line, the line sticks to it ; but it stretches so as to allow the insect to become entangled in other turns of the line. If it were not for this elasticity of the sticky line, most insects could readily tear themselves away before the spider had time to reach them. In making its web an orb weaver first spins a number of lines extending irregularly in various directions about the place where its orb is to be. This is the outer supporting framework. Often the first line spun is a bridge between two quite distant points. This is done as described on p. 25. Having a bridge across the place where the web is to be, it is an easy matter for the spider to stretch its other lines where it wishes them. I11 doing this it fastens a thread to one point, and then walks along to some other point, spin- INSECTS AND THEIR NEAR RELATIVES. 37 ning the thread as it goes, and holding it clear of the object on which it is walking by means of one of its hind legs. When the second point is reached the thread is pulled tight and fastened in place. After making the outer framework the radiating lines are formed. A line is stretched across the space so as to pass through the point which is to be the center of the orb. In doing this the spider may start on one side, and be forced to walk in a very roundabout way on the outer framework to the opposite side. It carefully holds the new line up behind it as it goes along, so that it shall not become entangled with the lines on which it walks; one or both hind feet serve as hands in these spinning operations. The spider then goes to the point where the centre of the orb is to be, and fast¬ ening another line there, it walk back to the outer frame¬ work, and attaches this line an inch or two from the first. In this way all of the radiating lines are drawn. The next step is to stay these radii by a spiral line which is begun at the center, and attached to each radius as it crosses it. The turns of this spiral are as far apart as the spider can con¬ veniently reach, except at the center of the web. All of the threads spun up to this stage in the construction of the web are dry and inelastic. The spider now proceeds to stretch upon this framework a sticky and elastic line, which is the most important part of the web, the other lines being merely a framework to support it. In spinning the sticky line the spider begins at the outer edge of the orb, and passing around it fastens this line to each radius as it goes. Thus a second spiral is made. The turns of this spiral are placed quite close together, and the first spiral, which is merely a temporary support, is destroyed as the second spiral pro¬ gresses. Figure 41 represents a web in which the second spiral is made over the outer half of the radii. In this fig¬ ure, aa represents the temporary stay-line; bb, the sticky spiral ; and cc} the fragments of the first spiral hanging from the radii. 38 THE STUDY OF INSECTS. Fig. 42. — Face of Epeira. The orb weavers (Family Epeiridce) are usually plump spiders, the abdomen being large, and often nearly spher¬ ical. The space between the eyes and front edge of the head is less than the region Fjg. 43.— Foot of Epeira. occupied by the eyes (Fig. 42). The eyes are arranged in two rows. The front legs are longer than the others. The feet have three claws (Fig. 43), and the spinnerets are all short. In some species of this family the male is much smaller than the female. Family ULOBORID^E (U-lo-bor'i-dae). The Curled-thread Weavers with Regular Webs. The Uloborids ( U-lo-bo'rids ). We have already described the thread-curling habits of the Dictynids (p. 32), and the curious organs called cribel- lum and calamistrum (Fig. 44), by which these curled threads are made (p. 23). Similar organs and a similar habit are possessed by the spi¬ ders of the family Uloboridce . These spiders, however, make webs which are p.G. 44.-Caiamistrum of reguiar jn form. There are only tw6 genera belonging to this family in the United States ; but as the webs made by these are very different, we will de¬ scribe both. The Triangle Spider, Hyptiotes cavatus (Hyp-ti'o-tes ca- va'tus). — This spider is common all over New England and the Middle States, and has been found as far to the south¬ west as Texas. Its web is most often found stretched be¬ tween the twigs of a dead branch of pine or spruce. At first sight this web appears like a fragment of an orb web (Fig. 45); but a little study will show that it is complete. The accompanying figure, by Dr. Wilder, who first described INSECTS AND THEIR NEAR RELATIVES . 39 the habits of this spider (see Popular Science Monthly , 1875), illustrates the form of the web. It consists of four plain lines corresponding to the radiating lines of an orb web, and a series of double cross lines, which are spun by the cribel- lum and calamistrum. From the point where the radiating lines meet a strong line extends to one of the supporting twigs. Near this twig the spider rests, pulling the web tight so that there is some loose line between its legs, as shown in the enlarged figure. When an insect becomes entangled in one of the cross lines, the spider suddenly lets go the loose line so that the whole web springs forward, and the insect is entangled in other cross threads. The spider then draws the web tight and snaps it again. This may be repeated several times before the spider goes out upon the web after its prey. Uloborus (U-lob'o-rus). — The spiders of this genus make round webs which resemble at first sight those of the Orb Weavers ; but they differ from the ordinary orb webs in that 40 THE STUDY OF INSECTS . the spiral thread is made of curled or hackled silk. These webs are nearly horizontal, and are usually made between stones or in low bushes. The spiders of this genus are not common, but they are widely distributed. They have not, however, been reported as yet from the Pacific coast. Family THOMISIDiE (Tho-mis'i-dae). The Crab Spiders . There are certain spiders which are called crab spiders, on account of the short and broad form of the body, and the curious fact that they can walk more readily sidewise or backward than forward. These spiders spin no webs, but lie in wait for their prey. They live chiefly on plants and fences, and in the winter hide in cracks and under stones and bark. Most of the spe¬ cies are marked with gray and brown, like the bark upon which they live. Some species conceal themselves in flow¬ ers, where they lie in wait for their prey. These are brightly colored, like the flowers they inhabit ; so that insects visiting flowers may alight within reach of a spider before seeing it. In this family the legs are turned outward and forward more than downward ; so that the body is carried close to #the ground. The second pair of legs are as long as or longer than the fourth pair. The ? eyes are small, nearly equal in size, and ar¬ ranged in two rows. ¥{uunaH^tiaU' One of the best-known members of this family is the female of Misumena vatia (Mi-su'me-na va'ti-a). This is milk-white, with sometimes a light crimson mark on each side of the abdomen, and is found within flowers (Fig. 46). Family LYCOSIDiE (Ly-cos'i-dae). The Running Spiders . Every collector of insects who has searched for speci¬ mens under stones and logs is familiar with the large, dark- :olore<2, hairy spiders often found in these places. These INSECTS AND THEIR NEAR RELATIVES. 41 spiders frequently attract especial attention by dragging after them a large gray ball (Fig. 47) ; this is the egg-sac, which the female carries about with her attached to her spinnerets. These spiders run swiftly ; and as they depend Fig. 47. — Lycosa and egg-sac. on the use of their legs for the capture of their prey, they are well termed Running Spiders. These spiders resemble in general appearance and in habits the Tarantulas of the South and the West. But none of our species attain the great size of some of the Tarantulas, and in the Running Spiders the claw of the mandibles moves horizontally instead of vertically. In this family the body is hairy and usually much longer than broad. The eyes differ markedly in size, and are arranged in three or four rows. The larger eyes are not in the front row. The legs are rather long and quite stout. Like the Tarantulas, some of the Running Spiders build tubular nests in the ground, which they line with silk. Some¬ times the entrance to these nests is concealed by small sticks and leaves, and sometimes the spi¬ der builds a regular turret over the entrance of its tube (Fig. 48). These nests are used merely as retreats, the spiders wandering forth in search of their prey. The larger members of our common species belong to the genus Lycosa (Ly-co'sa). These drag after them their egg-sacs as described above; and Fig. 48.— Entrance to nest of Turret Spider, Lycosa arenicola . (After Marx.) 42 THE STUDY OF INSECTS. when the young hatch they climb on their mother's back, and are carried about for a time. The females of the genus Dolomedes (Dol-o-me'des), which also belongs to this family, carry their egg-sac in their mandibles until the young are ready to hatch. At this time the mother fastens the egg- sac in a bush, and spins a web of irregular threads about it, among which the young spiders remain for a time. Family Attid/E (At'ti-dae). The Jumping Spiders. The Jumping Spiders are of medium size, with a short body and short stout legs (Fig. 49). They are common on plants, tlogs, fences, and the sides of buildings. They are very apt to attract attention by their pecul¬ iar appearance ; their short stout legs, bright colors, conspicuous eyes, and quick, jumping movements being very different from those of t ordinary spiders. The eyes are arranged in three or four rows ; Vxnudiiu7 {From front middle pair are the largest, and are Report onCoK* very conspicuous- These self-possessed spiders ton insects.) are able to stare an ordinary observer out of countenance. They move sidewise or backward with great ease, and can jump a long distance. They make no webs except nests in which they hide in winter or when moulting or laying eggs. In certain members of this family the body is longer than in the typical forms, and ant-like in appearance. Order Acarina (Ac-a-ri'na). The Mites. In this order the abdomen is unsegmented and fused with the thorax, giving the entire body a more or less sac- like appearance. In many the body is marked by numerous INSECTS AND THEIR NEAR RELATIVES . 43 transverse, fine lines, which are so impressed as to appear like the divisions between minute segments (Fig. 52). The majority of mites are very small ; but some, as certain Ticks, are of considerable size. With the exception of a single family the members of which bring forth living young, all mites are produced from eggs. As a rule, the newly-hatched mites have only three pairs of legs; but a fourth pair are added during growth. In Phytoptus , which infests plants, there arc only two pairs of legs. The mode of life of the different members of this order varies greatly : some are parasitic upon animals ; others infest living plants ; and many feed upon dead animal or vegetable matter, thus acting as scavengers. Among the mites that are parasitic upon animals are the various Ticks, which are very common in the warmer parts of our country. Figure 50 rep¬ resents the Cattle-tick of the Southern States. It should be remembered in this connection that the so-called Sheep-tick is a true insect, belonging to the order Diptera. The Itch-mite is a well-known parasite, infesting man and causing the disease known as the itch. The sensation character¬ istic of this disease is due to the burrowing of the mites in the skin ; and the efficiency of sulphur oint¬ ment in checking this disease is due to the fact that by the use of Figure 51 represents an itch-mite \ Parasitic mites are frequently found attached to insects ; a common species occurs beneath the wings of locusts. The best known of the mites that infest plants is the one commonly called the Red Spider. This lives upon house- plants ; and in the warmer parts of the country, where there Fig. 50. — The Cattle-tick, fe¬ male. Fig. 51. — An below ; Itch-mite : a, b. from above. from it the mites are killed, greatly enlarged. 44 THE STUDY OF INSECTS. is a dry season, it infests fruit-trees in the open air. As it thrives only in a dry atmosphere, it can be subdued upon house-plants by a liberal use of water. When it occurs upon plants in the open air it can be combated with any of the washes found useful in destroying scale insects. Some of the mites that infest plants produce galls. These galls are of various forms, but differ from those pro. duced by gall-flies (Family Cynipidce of the Order Hymen \ opterci) in having open mouths, from which the young mites escape. A common disease of the pear, known as the pear-leaf blister, is produced by a four-legged mite, Phytoptus pyri (Phy-top'tus py'ri) (Fig. 52). The blisters characteristic of Fig. 52 .—Phytoptus pyri, greatly enlarged. the disease are swellings of the leaf, within which there is a cavity affording a residence for the mites. Figure 53 repre- Fig. 53.— Diagram of gall of Phytoptus pyri : g* gall; n, m, normal structure of leaf ; o , open¬ ing of gall ; e , eggs. (After Soraur). sents a section of a leaf through one of these galls. Here the leaf is seen to be greatly thickened at the diseased part. On the lower side there is an opening through which the mite that started the gall entered, and from which young ) INSECTS AND THEIR NEAR RELATIVES. 45 unites developed in the gall can escape, in order to start new galls. In addition to the swelling of both surfaces of the leaf its internal structure is seen to be modified. In some parts there is a great multiplication of the cells, and in others a large part of the cells have been destroyed. Two eggs of mites are represented in this gall. As the season advances, and the galls become dry and brownish or black, the thickening of the leaf becomes less marked. In fact, in some cases there is a shrinkage of the parts affected. Fig- Fig. 54. — Section of leaf showing structure of gall in autumn : g, gall ; n , n , uninjured part of leaf ; o, opening of gall. ure 54 represents a section through a leaf collected and studied in October. Among the scavenger mites there are some that infest food products. Thus mites are sometimes found in cheese, in sugar, and in preserved meats. Class MYRIAPODA (Myr-iap'o-da). The Centipedes and the Millipedes. The members of this class are air-breathing Arthropods , in which the head is distinct from the thorax , and the thorax and abdomen form a continuous region, with from six to two hundred segments, each bearing a pair of legs. The head bears a single pair of ante nnce. The thousand-legged worms, as they are commonly called, are well-known and generally feared creatures. But few students find them attractive subjects of study ; never¬ theless it is well to know something about them, for some of them are dangerous animals, and some are harmless. A few species are injurious to agriculture, while others are to be 46 THE STUDY OF INSECTS. classed among our friends. And all of them are of interest to the naturalist as representatives of a distinct type of Arthropods. If we omit certain small and rather uncommon forms, the Myriapods may be classed in two orders ; one consisting of the Centipedes, the other of the Millipedes. Order Chilopoda (Chi-lop'o-da). The Centipedes . The centipedes can be recognized at a glance by the fact that each segment of the body bears a single pair of legs (Fig. 55). The body is usually flattened, and the antennse are long and many- jointed. Many species of centi- Fig. 55-— a Centipede. pedes are venomous. The poison glands open through the claws of the first pair of legs, which are bent forward so as to act with the mouth parts. These creatures abound in all parts of the United States; those which are found in the North are comparatively small, and rarely, if ever, inflict serious injury to man; but the larger species, which occur in the warmer regions, are said to extremely venomous. The centipedes are predaceous, feeding on insects ; they usually live under stones, logs, and bark. There is one spe¬ cies, Cermatia forceps (Cer-ma'ti-a), which has very long legs, and only fifteen pairs of them, which is often found running on the walls of houses, especially in the Southern States. We have never heard of this centipede biting a human be¬ ing, and as it feeds upon insects, especially cockroaches, it may be regarded as a welcome visitor in houses. INSECTS AND THEIR NEAR RELATIVES. 47 Order CHILOGNATHA (Chi-log'na-tha). The Millipedes . The millipedes differ from the centipedes in having two pairs of legs on each of the body segments except the first three. The body in most of them is not flattened as with the centipedes, and the antennae are comparatively short and few jointed (Fig. 56). Fig. 56. — A Millipede. The millipedes, as a rule, live in damp places and feed on decaying vegetable matter. They are harmless, except that occasionally they feed upon growing plants. CHAPTER III. Class Hexapoda (Hex-ap'o-da). The Insects . The members of this class are air-breathing Arthropoda , with distinct head , thorax , and abdomen. They have one pair of antenna, three pairs of legs , and usually one or two pairs of wings in the adult state . There are about us on every side myriads of tiny crea¬ tures that are commonly passed unnoticed, and even when observed, they are usually thought to be unworthy of serious consideration. But all life is linked together in such a way that no part of the chain is unimportant. Frequently upon the action of some of these minute beings depends the mate¬ rial success or failure of a great commonwealth. The intro¬ duction and spread of a single species of insect (the Cot- tony-cushion Scale) in California threatened the destruction of the extensive orchards of that State ; thousands of trees perished. The introduction of a few individuals of a partic¬ ular kind of Lady-bug {Vedalia cardinalis ), which feeds upon this pest and multiplies rapidly, soon checked the evil, and has nearly removed the pest from the State. But insects are of interest to us for other reasons than the influence they may have upon our material welfare ; the study of them is a fruitful field for intellectual growth. It is not a small matter to be able to view intelligently the facts presented by the insect world, to know something of what is going on around us. And so rich is this field that no one gains more than a mere smattering concerning it. 48 HEXAPODA. 49 We know as yet comparatively little about the minute structure of insects ; the transformations and habits of the greater number of species have not been studied; and the blood-relationship of the various groups of insects is very imperfectly understood. If, therefore, one would learn something of the action of the laws that govern the life and development of organized beings, and at the same time ex¬ perience the pleasure derived from original investigation, he cannot find a better field than is offered by the study of in¬ sects. But it is not necessary that one should have the tastes and leisure required for careful scientific investigation in order to profit by this study. It can be made a recreation, a source of entertainment when we are tired, a pleasant oc¬ cupation for our thoughts when we walk. Any one can find out something new regarding insect architecture — the ways in which these creatures build nests for themselves or foi their young. It is easy to observe remarkable feats of en¬ gineering, examples of foresight, wonderful industry, unre¬ mitting care of young, tragedies, and even war and slavery. The abundance of insects makes it easy to study them. They can be found wherever man can live, and at all seasons. This abundance is even greater than is commonly supposed. The number of individuals in a single species is beyond com¬ putation : who can count the aphids or the scale-bugs in a single orchard, or the bees in a single meadow ? Not only are insects numerous when we regard individ¬ uals, but the number of species is far greater than that of all other animals taken together. The number of species in a single family is greater in several cases than the number of stars visible in a clear night. The word insect is often applied incorrectly to any mi¬ nute animal ; and even among naturalists there is some lack of uniformity in its use. Some writers include under this term the Arachnida and Myriapoda, as well as the Six-footed Insects. But the great majority of entomologists restrict 5 50 THE STUD Y OF INSECTS . the term to the Hexapoda, and it is in this sense that we use it. The name Hexapoda is from two Greek words : hex, six ; and pons, foot. It refers to the fact that the members of this order differ from other Arthropods in the possession of only six feet. Insects breath by means of a system of air-tubes (tra¬ cheae) which extends through the body. This is true even in the case of those that live in water and are supplied with gill-like organs (the tracheal gills ; see p. 75). The head is distinct from the thorax, and bears a single pair of antennae; in these respects they are closely allied to the Myriapods. But they can be easily distinguished by the number of their feet, and, usually, also by the presence of wings. The Metamorphoses of Insects. Nearly all insects in the course of their lives undergo re¬ markable changes in form. Thus the butterfly, which de¬ lights us with its airy flight, was at one time a caterpillar; the bee, which goes so busily from flower to flower, lived first the life of a clumsy, footless grub ; and the graceful fly was developed from a maggot. In the following pages considerable attention will be given to descriptions of the changes through which various insects pass. It is our wish in this place merely to define certain terms which are used in describing these changes. Development without Metamorphosis. — In one of the orders of insects, the Thysanura, the young insect just hatched from the egg is of the same form as the adult insect. These insects merely grow larger, without any more marked change in form than takes place in our own bodies during our life. They are said, therefore, to develop without metamorphosis. Incomplete Metamorphosis. — There are many insects which undergo a striking change of form during their life* although the young greatly resembles the adult. Thus a young locust just out from the egg can be easily recognized as a locust. HEXAPOD A. 51 It is of course much smaller than the adult, and is not fur¬ nished with wings. Still the form of the body is essentially the same as that of the adult (Fig. 57). (The hair-line above the figure indicates the natural size of the insect.) After a time rudimentary wings appear; and these increase Fig. 57.— Nymph of Melanoplus , Fig. 58.— Nymph of Melanoplus , first stage. (After Emerton.) second stage. (After Emerton.) Fig. 59. — Nymph of Melanoplus , third stage. Fig. 60.— Nymph of Melanoplus , fourth (After Emerton.) stage. (After Emerton.) 1 - 1 Fig. 61 —Nymph of Melanoplus , fifth Fig. 62.— Melanoplus, adult, stage. (After Emerton.) in size from time to time till the adult state is reached (Figs. 57 to 62). During this development there is no point at which the insect passes into a quiescent state corresponding to the chrysalis state of a butterfly. Those insects which, like the locust, when they emerge from the egg resemble in form the adult, but still undergo some change, arc said to un¬ dergo an incomplete metamorphosis. In other words, after leaving the egg they do not undergo a complete change of form. Complete Metamorphosis . — Still other insects, like the but- 52 THE STUDY OF INSECTS . terflies, beetles, bees, and flies, leave the egg in an entirely different form from that which they assume when they reach maturity. A butterfly begins its active life as a caterpillar. It feeds and grows, and when full grown changes to a chrys- salis. In this stage it has very little resemblance to a cater¬ pillar. After a time there bursts forth from the chrysalis shell the butterfly, which looks very little like the chrysalis, and still less like the caterpillar from which it came. In a similar way, from the egg laid by a fly upon a piece of meat there hatches, not a fly, but a footless, worm-like maggot. This when fully grown changes to a quiescent object corre¬ sponding to the chrysalis of a butterfly. Later from this ob¬ ject there escapes a winged fly like that which laid the egg. Those insects, like the butterflies and flesh-flies, which when they emerge from the egg bear almost no resemblance in form to the adult insect, are said to undergo a complete met¬ amorphosis. In other words, the change of form undergone by the insect is a complete one. How Insects grow — Molting . — The skin of an insect is hard¬ ened more or less by a horny substance known as chitine (chi'tine). This hardening usually occurs to a much greater extent in adult insects than it does in the young. But in all the skin becomes so firm that it cannot stretch enough to allow for the growth of the insect. The result is, that from time to time an in¬ sect’s skin becomes too small for it, and must be shed. But before this is done a new skin is formed beneath the old one; then the old skin bursts open, and the insect crawls forth, clothed in a soft skin, which stretches to accommodate the increased size of the animal. Very soon, however, this new skin becomes hardened with chitine, and after a time it in turn must be shed. This shedding of the skin is termed molting , and the cast skin is some- HEXAPODA. 53 times referred to as the exuvicz (ex-u'vi-ae). Insects differ greatly as to the number of times they molt : many species molt only four or five times, while others are known to molt more than twenty times. Figure 62 a represents the cast skin of a Dragon-fly clinging to a reed. The Egg . — This is the first stage in the existence of any insect, although in some few instances the egg remains in the body of the mother till it hatches. But almost always the eggs arc laid by the mother insect on or near the food which gives nourishment to the young. Many of the most interesting habits of insects are connected with the care of the eggs by the parent. The eggs may have smooth oval shells ; but often the shells are beautifully ribbed f.o.^e^oI c^n-wo™, and pitted (Fig. 63), and some- on Cotton insects.) times they are ornamented with spines, and are frequently exquisitely colored. The Larva. — This is the second stage of an insect’s life, and is the form that hatches from the egg. Familiar exam¬ ples of larva; are caterpillars, maggots, and grubs (Fig. 64). Fig. 64.— A caterpillar, the larva of a moth. In fact, nearly all the creatures commonly known as worms are larvae of insects. Away from the ocean we find but few worms, except earthworms, leeches, “ hair-snakes, and worm parasites in the intestines of men and animals. Nearly all the rest, except millipedes and centipedes, are larvae of insects, and finally change to forms with wings. 54 THE STUDY OF INSECTS. The larval stage is devoted to growth/ the sole business of a larva being to eat and grow. All molting, because of in¬ creased size, is done in the larval stage, later molts are simply for change of shape. The Pupa. — This is the third stage in the life of an in¬ sect, and is ordinarily a period of inaction, except that rapid and wonderful changes go on within the body. Very few pupae, like those of mosquitoes, are active. Usually pupae have no power of moving around, but many of them can squirm when disturbed. When the last skin of the larva is thrown off the pupa is re¬ vealed ; it is an oblong object, Fig. 65.-A pupa of a large moth. frequently apparently headless and footless. In many pupae the skin is a shiny covering like porcelain. If a pupa be examined closely the antennae and legs and wings may be seen ; these are folded up closely and soldered to the breast in the case of tne moths and butterflies (Fig. 65), but free in case of the bees, ants, and beetles. The Chrysalis . — This term is often applied to the pupa of a butterfly. The word is derived from a Greek word mean¬ ing gold, and came into use because of the golden dots and markings on many of the butterfly pupae. The Cocoon. — Many larvae, especially those of moths, when full grown, spin about the body a silken case, so that when they change to helpless pupae they may be protected from enemies, and from rain and snow ; these silken cases are called cocoons. They are frequently made within a rolled leaves (Fig. 66), or beneath grass and rubbish on the ground, or in cells below the ground. Some hairy caterpil¬ lars make cocoons largely of their own hairs, which they fasten together with a film of silk. The Nymph . — The terms larva and pupa are only ap. plied to the early stages of those insects that have a com- HEX A POD A. 55 plete metamorphosis; for in the case of other insects there is no distinct pupa stage. When reference is made to the young of an insect that undergoes an incomplete metamor- Fig. 66.— A large cocoon within a roiled leaf. phosis it is called a nymph . This term is applied to all stages of such an insect from the time they hatch from the egg until they shed their skin for the last time. When a nymph first hatches it has no signs of wings ; but after it molts several times two projections appear on each side of the thorax. These projections become larger and larger, and more wing-like in form with each successive molt. Usually the change in the size of these organs, between the last nymph stage and the adult stage, is much greater than that of any previous molt. With the nymphs of certain families, dragon-flies, crickets, grasshoppers, and locusts, the front pair of developing wings extend back beneath the hind pair instead of covering them ; and by this inverted position of the wings the nymphs may be distinguished from the adults, even in those cases where the adults have only rudimentary wings. The Adult . — This is the last stage or the mature form of the insect. Almost all adult insects except Thysanura have wings, although there are numerous exceptions to the rule ; for there are many cases where wings have been lost through disuse. An insect never grows after it reaches the adult stage, and therefore never molts. There is a popular belief that a small fly will grow into a large fly, but this is not true, for after any insect gets its perfect wings it can 56 THE STUDY OF INSECTS. grow no larger, except that in case of females the body may be distended by the growth of eggs within it. While many adults eat more or less, it is only to sustain life, and not for growth. Indeed, many adult insects take very little food, and some have lost their mouth-parts entirely, through disuse. The adult stage usually lasts for a considerably shorter time than the larval or nymph stages. In fact, it seems planned in the economy of nature that the grown-up insects should live only long enough to lay eggs, and thus secure the perpetuation of the species. The External Anatomy of Insects. The subject of insect anatomy is separated into two divi¬ sions : one, treating of the structure of the body-wall or skeleton; the other, of the internal organs. The former is termed external anatomy ; the latter, internal anatomy . In our own bodies we find a central framework or skele¬ ton, about which are arranged the muscles, blood-vessels, nerves, and other organs. But insects are constructed on an entirely different plan : with them the supporting skele¬ ton is outside, and the muscles, nerves, and other organs are within this skeleton. The difference can be well seen if the figure showing the internal structure of the leg of a May-beetle (Fig. 67) be compared with one of our own limbs, either arm or leg. Fig. 67.— Leg of May-beetle. (After Straus-Durckheim.) The body of an insect is built on the same plan as are its legs. The outside of the body is more or less firm, being hardened by chitine ; and this firm outer wall supports the muscles and other organs, thus serving as a skeleton. The skeleton is therefore, in general outline, a hollow cylinder. HEXAPODA. 57 This hardening of the body-wall is not continuous, but takes place in a series of more or less regular, ring-like bands, which give the well-known seg¬ mented appearance characteristic of insects, and the animals closely Fig. 68. — a Larva, allied to them. Between the hardened ring-like segments the body-wall remains soft and flexible. In this way provi¬ sion is made fcr the various motions of the body. The ring-like nature of the segments of the body is best seen in larvae (Fig. 68), and in the hinder part of an adult insect (Fig. 69). The movements of the legs, antennae* and certain other appendages are provided for in the same way ; each one is a cylinder made up of several segments, and between these seg¬ ments the wall of the cylinder remains flexible. When a single segment of the body is examined, the hardened portion is not found to be a continuous ring, but is seen to be made up of several portions more Fig. 69.-A Mole Cricket, or less movable upon each other. Such a hardened portion of the body-wall is termed a sclerite (scle'rite). The sclerites constitute the greater part of the body-wall, the soft membranous portions separating them being in most cases narrow. Usually these narrow portions are mere lines; they are then called sutures (sut urs). Frequently the sutures become entirely effaced. We are therefore often unable to distinguish certain sclerites in one species of insect which we know to exist in another. In such cases the effaced sutures are said to be obsolete . If the central portion or thorax of an adult insect be examined, numerous sclerites and sutures can be observed (Fig. 70). THE STUDY OF INSECTS. 5S The subject of external anatomy of insects consists very largely in a study of the sclerites of which the different segments of the body and of its appendages are composed. This part of the subject is quite difficult, and will not be discussed here. It is treated, however, in the discussion of the characters used in the classification of the Coleoptera given on pages 499 to 504. These pages should be carefully studied before attempting to use the table that follows them, Fig. 70. — Side-view of Locust with wings removed Fig. 71.— Wasp, with head, thorax, and abdomen separated. The segments of the body in a fully developed insect are grouped into three regions: head, thorax, and abdomen (Fig. 71). In the larval state this grouping of the segments is not well shown. The Head and its Appendages. The head is the first of the three regions of the body. It is supposed to be formed of several body-segments grown together ; but entomologists differ in their views as to the number of segments that have entered into its composition. The head bears the compound eyes, the simple eyes, the antennae, and the mouth-parts. The Compound Eyes. — On each side of the head of an adult insect is an organ, which is recognized at once as an eye. But when one of these eyes is examined with a microscope it is found to present an appearance very different from that of the eye of higher animals ; its surface a large number of six-sided divisions Fig. 72. — Part of com- fiour.d eye, greatly en- arged. is divided into HEXAPODA. 59 (Fig. 72). A study of the internal structure of this organ has shown that each of these hexagonal divi¬ sions is the outer end of a distinct eye (Fig. 73). Hence what at first appears to be a single eye is really an organ composed of hundreds of eyes ; it is termed, therefore, a compound eye. Each of the small eyes of which a compound eye is composed is termed an ommatidium. The number of ommatidia of which a compound eye is composed varies greatly : there may be not more than fifty, as in certain ants, or there may be many thousand, as in a butter¬ fly or a dragon-fly. Compound eyes are not found in larvae, though they may possess a group of simple eyes on each side of the head. The Simple Eyes . — In addition to the com¬ pound eyes, many adult insects possess simple eyes. These are situated between the com¬ pound eyes. They vary in number from one to four; the most common number is three (see Fig. 71). The simple eyes are usually termed ocelli; sometimes, stemmata (stem'ma-ta). When the term ocelli is used in descriptive works, if there is nothing in the context to Fig n _ Three indicate the contrary, it is almost invariably of a May- bee tie. (After Grenach- er.) The pig¬ ment has been dissolved away from two of them. F, corneal facet : K, crystal¬ line cone ; /, pig¬ ment-sheath ; F, chief pigment¬ cell ; p ", pig¬ ment-cells of the second order ; R , retinulas. applied to the simple eyes, and not to the ele¬ ments of the compound eyes. In the same way the term eye usually refers to the com¬ pound eyes, unless otherwise indicated by the context. The Antennce . — The antennae are a pair of jointed appendages inserted in the head in front of the eyes or between them. They vary in form. In some insects they are thread-like, consisting of a series of similar segments; in others certain segments are greatly modified in form. oo THE STUDY OF INSECTS. The various forms of antennae are designated by special terms. The more common of these forms are represented in Figure 74. These are as follows : 1. Setaceous (se-ta'ceous) or bris¬ tle-like, in which the segments are successively smaller and smaller, the whole organ tapering to a point. 2. Filiform (fil'i-form) or thread¬ like, in which each segment is of nearly uniform thickness throughout its length; and the antenna as a whole tapers gradually, if at all, to¬ wards the tip. 3. Moniliform (mo-nil'i-form) or necklace-form, in which the segments are more or less globose, suggesting a string of beads. 4. Serrate (ser'rate) or saw-like, in which the segments are triangular, and project like the teeth of a saw. 5. Pectinate (pcc'ti-nate) or comb-like, in which the seg¬ ments have long processes on one side, like the teeth of a comb, or on both sides, like a feather. 6. Clavate (cla'vate) or club-shaped, in which the seg¬ ments become gradually broader, so that the whole organ assumes the form of a club. 7. Capitate (cap'i-tate) or with a head, in which the terminal segment or segments form a large knob. 8. Lamellate (jam'el-late), in which the segments that compose the knob are extended on one side into broad plates. The Mouth-parts . — No set of organs in the body of an in¬ sect vary in form to a greater degree than do the mouth-parts. Thus with some the mouth is formed for biting, while with others it is formed for sucking. Among the biting insects some are predaceous, and have jaws fitted for seizing and Fig. 74. — Various forms of an¬ tennae. HEXAPODA „ 61 tearing their prey ; others feed upon vegetable matter, and have jaws for chewing this kind of food. Among the suck¬ ing insects the butterfly merely sips the nectar from flowers, while the mosquito needs a powerful instrument for piercing its victim. In this place the typical form of the mouth- parts as illustrated by the biting insects is described. The various modifications of it presented by the sucking insects are described later, in the discussion of the characters of those insects. In the biting insects, the mouth-parts consist of an upper lip, the labrutn (la'brum) (Fig. 75, 8); an under lip, the labium (la'bi-um) (Fig. 75, 12); and two pairs of jaws between them. These jaws open sidewise, instead of in a vertical direction, as do the jaws of the higher animals. The upper pair of jaws are called the mandibles (mail'd i-bles) (Fig. 75, 10); the lower pair, the maxillce (max-iTlae) (Fig. 75, n). There may be also within the mouth one or two tongue-like organs, the epipharynx (ep-i-phar'ynx) and hypopharynx (hy - po - phar'ynx) (Fig. 7 5> I3)« The epipharynx is Fig. 75.— Mouth-parts of the Red- legged Locust. attached to the upper wall of the cavity of the mouth, and the hypopharynx to the lower. The position of the hypopharynx is quite analogous, therefore, to that of our tongue. The mandibles vary much in form, but usually each consists of a single sclerite. The maxillae of biting insects, on the other tic. ^s.-Maxiiia of a hand, are very complicated organs, each com¬ posed of several sclerites. Each maxilla bears an appendage consisting of several segments ; these 62 THE STUDY OF INSECTS. appendages are termed the maxillary palpi. In the maxillae of certain biting insects, as the grasshoppers and the ground beetles, there is an appendage usually consisting of two segments : this is the galea (ga'le-a) or outer lobe. In some of these insects, as the ground-beetles and the tiger- beetles, the galea is shaped like a palpus, and thus there appears to be two pairs of maxillary palpi (Fig. 76). The labium is furnished with a pair of jointed appendages ; these are the labial palpi (Fig. 75, 12, d). The Thorax and its Appendages. The thorax is the second or intermediate region of the body ; it is the region that bears, in the adult insect, the organs of locomotion, the legs, and the wings when they are present. This region is composed of three of the body- segments more or less firmly joined together ; the segments are most readily distinguished by the fact that each bears a pair of legs. In winged insects, the wings are borne by the second and third segments. The first segment of the thorax, the one next to the head, is named the prothorax ; the second thoracic segment is the mesothorax ; and the third, the metathorax. The Legs. — Each leg consists of the following parts, beginning with the one next to the body (see Fig. 77): coxa , trochanter , femur , tibia, and tarsus. Each of these parts consists of a single seg¬ ment except that in certain Hymenoptera the trochanter consists of two segments (Fig. 77, /), and in most insects the tarsus consists of several seg¬ ments. The number of seg. ments of the tarsus varies from the most common number is five. Frequently the first segment of the tarsus is much longer than either of a b c Fig. 77. — Legs of insects : a. Wasp ; 5, Ichne\imon-fly; c , Bee ; t, trochanter; in, metatarsus. one to six HEXAPODA. 63 the other segments, and it may also differ greatly in form from them ; under such circumstances it is sometimes desig¬ nated the metatarsus (met-a-tar'sus) (Fig. 77, ;//). The last segment of the tarsus usually bears one or two claws. On the ventral surface of the segments of the tarsus in many insects are cushion-like structures ; these are called pulvilli (pul-vil-li). The cuticle of the pulvilli is traversed by numerous pores which open either at the surface of the cuticle or through hollow hairs, the tenent hairs , and from which ex¬ udes an adhesive fluid that enables the insect to walk on the lower surface of objects. The wings. — The two pairs of wings are borne by the mesothorax and metathorax ; the prothorax never bears wings. In form, an insect's wing is a large membranous append¬ age, which is thickened along certain lines. These thickened lines are termed the veins or nerves of the wing ; and their arrangement is described as the venation or neuration of the wings. The thin spaces of the wings which are bounded by the veins are called cells . When a cell is completely sur¬ rounded by veins it is said to be closed ; but when it extends to the margin of the wing it is said to be open . The wings of different insects vary greatly in structure, and thus afford excellent distinctions for the purposes of classification. The various parts of the wing have, there¬ fore, received special names. There is considerable lack of uniformity among entomologists as to the names applied to these parts ; but we have adopted the set of terms defined below as representing the best usage. An insect's wing is more or less triangular in outline ; it therefore presents three margins : the costal margin , or costa (Fig. 78, a , li) ; the outer margin (Fig. 78, b, c) ; and the inner margin (Fig. 78, c, d). The angle at the base of the costal margin (Fig. 78, a) is the humeral angle (hu'me-ral) ; that between the costal mar¬ gin and the outer margin (Fig. 78, b) is the apex of the wing ; □4 THE STUDY OF INSECTS . and the angle between the outer margin and the inner mar¬ gin (Fig. 78, c ) is the a7ial a?igle (a'nal). There have been many different sets of names applied to the veins of the wings. Not only have the students of each Fig. 78. — Fore wing of a butterfly with the veins and cells numbered. order of insects had a peculiar nomenclature, but in many cases different students of the same order of insects have used different sets of terms. This condition of affairs was incident to the beginning of the science, the period before the correspondence of the veins in the different orders had been worked out. But now the time has come when it seems practicable to apply a uniform nomenclature to the wing veins of all orders; and the following set of terms is proposed for that purpose. The principal veins of the wing, those that arise at or near the base of the wing, are termed, beginning with the one lying on the costal margin, the costa (cos'ta), the subcosta , the radius (ra'di-us), the media (me'di-a), the cubitus (cu'bi- tus), and the anal veins . The radius, media, and cubitus are usually branched, and there may be several anal veins. In addition to the principal or longitudinal veins, there may be a greater or less number of cross-veins — veins extend¬ ing transversely from one longitudinal vein to another. HEXAPODA . 65 The principal veins may be designated by numbers as well as by names ; the following table indicates the correspondence of the names and numbers : Cubitus = vein VII. 1st anal vein = vein VIII. 2d anal vein = vein IX. 3d anal vein = vein XI. Costa = vein I. Subcosta = vein II. Radius = vein III. Media = vein V. It was formerly believed that in certain insects three other longitudinal veins were present ; these were numbered IV, VI, and X respectively ; hence these numbers are omitted in the above table. At the time the first edition of this book was written, it was thought best to designate the veins by numbers; and conse¬ quently numbers are used in the following pages much more generally than are the names of the veins. But owing to a lack of uniformity in the numbering of the veins by different writers, it is now clear that the names are to be preferred. In Fig. 79. — Diagram representing the typical arrangement of the wing-veins, includ¬ ing the four more important cross-veins: /6, numeral cross-vein; r-m , radio- medial cross-vein ; m, medial cross-vein ; m-cu, medio-cubital cross-vein. the lettering of figures abbreviations of the names can be used as is done in Figure 79. The divisions of a branched vein are numbered, beginning with the one nearest the costal margin of the wing ; and these numbers are indicated by sub-figures. For example, 6 66 THE STUDY OF INSECTS . the five branches of the typical radius, or vein III, are designated either thus, Ru R2, R3, R4, R5 ; or thus, mu III2, Ills, III4, Ills- When two or more branches of a branched vein coalesce, the compound vein is designated by an expression indicating this coalescence, as III2+8 or R2+8. In this way it is possible to indicate some of the changes that have taken place in the de¬ velopment of the species; and to make use of them in working out the classification of the group to which the species belongs. The cells of the wing are designated by applying to each the number or the abbreviation of the name of the vein that forms its cephalic (front) margin. In Figure 78 the veins are designated by numbers at the margin of the figure ; the cells by numbers within the figure. When a cell is divided by a cross-vein the parts are numbered, as in the case of cell V2 in Figure 497, page 422. The Abdomen and its Appendages. The abdomen is the third or caudal region of the body. Its segments are more simple, distinct, and ring-like than those of the other regions. The number of segments of which it appears to be composed varies greatly. In the Cuckoo-flies ( Chrysidida ) there are usually only three or four visible, while in many other insects nine appear. Except in the lowest order of insects ( Thysanura ) the abdomen of the adult bears no locomotive appendages. But many larvae have fleshy appendages which aid in locomotion : these are termed prolegs . In the adult the end of the body in many families is furnished with jointed filaments — the cerci} and caudal setcz. Frequently also the body is furnished in the male with organs for clasping— the claspers ; and in the female with saws, pierces, or borers — the ovipositor . In the female of certain insects there is a sting , a modified ovipositor, which is used as an organ of defence ; and the abdomen of plant- lice and certain other insects bears a pair of tubes or tuber- HEXAPODA. 67 cles, through which a waxlike material is excreted : these are commonly called honey-tubes ; they are also termed cornicles , nectaries , or siphuncles ; see page 157. The Internal Anatomy of Insects, (For advanced students .) As has been shown in the preceding pages, the body-wall serves as a skeleton, being hard, and giving support to the other organs of the body. This skeleton may be represented, therefore, as a hollow cylinder. We have now to consider the arrangement and the general form of the organs contained in this cylinder. For the details of the structure of th . internal organs the student is referred to more special works. The accompanying diagram (Fig. 80), which represents a vertical, longitudinal section of the body, will enable the student to gain an idea of the relative position of some of the more important organs. The parts shown in the diagram are as follows: The body-wall, or skeleton Fig. 80.— Diagram showing the relation of the internal organs. (s); this is made up of a series of overlapping segments ; that part of it between the segments is thinner, and is not hardened with chitine, thus remaining flexible and allowing for the movements of the body. Just within the body-wall, and attached to it, are represented a few of the muscles (m) ; it will be seen that these muscles are so arranged that the contraction of those on the lower side of the body would bend it down, while the contraction of those on the opposite side would act in the opposite direction. The alimentary canal (a) occu¬ pies the centre of the body, and extends from one end to the other. The heart (//) is a tube open at both ends, and lying between the alimentary canal and the muscles of the back. The central part of the nervous system (u) is a series of small masses of nervous matter connected by two longitudinal cords: one of these masses, the brain, lies in the head above the alimentary canal ; the others are situated, 68 THE STUDY OF INSECTS. PLATE II. A Caterpillar sCossus I ign i per da). (After Lyonet.) FlG. i.~-Caterpillar opened on the ventral middle line. Fig. 2. — Caterpillar opened op the dorsal middle line. _ 1, principal longitudinal tracheae ; 2, central nervous syj> tem : 3, aorta; 4, longitudinal dorsal muscles; 5, longitudinal ventral muscles* 6, wings of the heart; 7, tracheal trunks arising near spiracles; 8, reproductive organs ; 9, vertical muscles; io, last abdominal ganglion. HEX A P OD A . 69 one in each segment, between the alimentary canal and the layer of muscles of the ventral side of the body ; the two cords connecting these masses, or ganglia, pass one on each side of the oesophagus to the brain. The reproductive organs (r) lie in the cavity of the abdo¬ men and open near the caudal end of the body. The respiratory organs are omitted from this diagram for the sake of simplicity. The Muscular System . — We find in insects a wonderfully large number of muscles. Those that move the segments of the body form several layers just wit.iin the body-wall. The two figures on Plate II represent two caterpillars which have been split open lengthwise, one on the middle line of the back and one on the opposite side ; in each case the alimentary canal has been removed, so that only those organs that are attached quite closely to the body-wall are left. From a study of these figures some idea can be obtained of the number and arrange¬ ment of these muscles. It should be borne in mind, however, that only a single layer of muscles is represented in these figures — the layer which would be seen if a caterpillar were opened in the way indicated. When these muscles are cut away many other muscles are found ex¬ tending obliquely in various directions between these muscles and the body-wall. The muscles of insects appear very differently from those (the lean meat) of higher animals. In insects the muscles are either colorless and transparent, or yellowish white ; and they are soft, almost of a gelatinous consistence. When hardened by alcohol or otherwise, and examined with a microscope, they are seen to be crossed by numerous transverse lines, like the voluntary muscles of Vertebrates. As a rule, the muscles of insects are composed of an immense number of distinct fibres, which are not enclosed in tendinous sheaths as with Vertebrates. But the muscles that move the appendages ol the body are furnished with a tendon at the end farthest from the body (Fig. 81). Fig. 8i.— Leg of May-beetle. (After Straus-Durcklieim.) Notwithstanding the soft and delicate appearance of the muscles of insects, they are leally very strong. One has only to observe the power of leaping possessed by many species to be convinced of this. JO THE STUDY OF INSECTS. PLATE III. A Cockroach ( Periplaneta orientalis). (From Rolleston). a, antennae; b\. 62, £3, tibiae; c, anal cerci ; d, ganglion on recurrent nerve upon the crop ; e , salivary duct : y, salivary bladder; g, gizzard ; l \ , hepatic coeca; 1 , chylinc stomach : j\ Malpighian vessels; k, small intestine; /, large intestine ; tn , rectum; ft- first abdominal ganglion ; o, ovary ; /, sebaceous glands. HEXAPODA. 71 And the rapidity of their action is even more wonderful than their strength. This rapidity is best illustrated by the muscles that move the wings. Every one has observed gnats and other Hies poising in mid air by a movement of the wings so rapid that the eye cannot follow it. Physicists have been able, however, to count these vibrations by de¬ termining the pitch of the musical note produced in this way. And they tell us that certain gnats vibrate their wings 15,000 times per second. The Alimentary Canal. — The typical position of this is represented in the diagram (Fig. 80); and on Plate III, illustrating the anatomy of a cockroach, its form in that insect is shown. In larvae it is a nearly straight tube, extending from one end of the body to the other. But in adult insects it is usually much longer than the body, and is consequently more or less folded. It is composed of parts differing in form and use. To these parts names have been given similar to those used to designate the corresponding parts in higher animals ; thus we distinguish a pharynx, an cesophagns , sometimes a crop , some- times a gizzard , a stomach , a small intestine , and a large intestine . The Adipose Tissue , or Fat— On opening the body of an insect, especially of a larva, one of the most conspicuous things to be seen is fatty tissue, in large masses. These often completely surround the alimentary canal, and are held in place by numerous branches of the tracheae with which they are supplied. Other and smaller masses of this tissue adhere to the inner surface of the abdominal wall, in the vicinity of the nervous system, and at the sides of the body. In a full- grown larva of Corydalis cornuta I have found the adipose tissue to be greater in bulk than all of the other organs found inside of the muscular walls of the body. In adult insects it usually exists in much less quantity than in larv®. The Blood-vessels.— In insects all parts of the body cavity that are not occupied by the internal organs are filled with blood. Thus the alimentary canal is completely surrounded with blood, and all the spaces between the muscles are filled by this fluid. This is a very different arrangement from what occurs in our own body, where the blood is con¬ tained in a system of tubes, the arteries and the veins. We find, however, that insects are not entirely deprived of blood-vessels. For there is one which lies above the ali¬ mentary canal, just within the middle line of the back. See Figure 80, //, and Plate II, 1. This extends from near the caudal end of the abdomen through the thorax into the head. That part of this system that lies in the abdomen Fig. 82. — Dia¬ gram of a part of the heart of a May-beetle. 72 THE STUDY OF INSECTS. is usually termed the heart. This is a somewhat complicated organ consisting of several chambers arranged in series, and each communicating with the one in front of it by an opening fur¬ nished with valves. The number and form of these chambers differ in different in¬ sects. Fig. 82 represents the heart of a May - beetle. These chambers not only communicate with each other, but com¬ municate with the body-cavity by means of side openings, which are also furnished with valves. These two sets of valves act in such a way that when a chamber of the heart contracts a stream of blood is forced towards the head, and when it expands the blood rushes into it through the side open¬ ings, and from the chamber behind it. At¬ tached to the lower surface of the heart and extending out to the side of the body there is on each side a series of triangular muscles: these have been termed the wings ^UfterStrawOurelScSn^1', of the heart. (Plate II, 6, and Fig. 83. c). tateriir“Pf'Cheart "showing In Figure * they are represented cut away valves ; c. ventral aspect of from the caudal part of the heart. The heart and wing-muscles— the . , ,. . , muscles are represented as prolongation of the heart, which extends part^^eheart1;^ dorsal through the thorax and into the head, is aspect of heart. termed the aorta. The blood is forced by the heart through the aorta into the head, where it escapes into the body cavity. From this point it flows through the body cavity in regular streams, which have definite di¬ rections, but which are not included in vessels. They, like the ocean currents, are definite streams with liquid shores. The blood is usually colorless, or slightly tinged with green ; but its circulation is made conspicuous by the movements of the large corpuscles with which it abounds. In transparent insects it can be seen pouring forth from the cephalic end of the aorta, bathing first the brain, and then passing to all parts of the body, even out Into the appendages. By tracing the course of any one of these currents it will be found to flow, sooner or later, to the cavity between the wings of the heart and the back in which the heart rests, and from which it receives its blood. The Nervous System.— The central part of the nervous system, as HEXAPODA . 73 already indicated, consists of a ganglion in the head above the oesoph¬ agus, and of a series of ganglia, typically one for each segment of the body, lying on the floor of the body cav¬ ity, and connected by two longitudinal cords. In the head, one of these cords passes on each side of the oesophagus, from the brain to another ganglion in the head below the oesophagus, thus forming a nervous collar about the alimentary canal. From each ganglion nerves arise, which supply the ad¬ jacent parts; and from the thoracic ganglia nerves extend to the legs and wings. This series of ganglia is really a double one; but each pair of ganglia arc more or less closely united on the middle line of the body, and often appear as a single ganglion. Figure 84 gives a general view of the nervous system of Corydalis cornuta. From the brain (a) two large nerves extend to the compound eyes, and a smaller pair to the antennae; the sub- oesophageal ganglion (/;) supplies the mouth- parts with nerves ; and each of the thoracic and abdominal ganglia supplies its segment of the body. How Insects Breathe — The Respiratory System. — A common mis¬ take made by beginners in the study of Entomology is to suppose that insects breathe through the mouth as do the higher animals. Many a beginner has carefully poured chloroform on the head of an insect in the expectation of killing it in that way, and has been sur¬ prised at his poor success. The truth is, insects breathe through their sides. If an insect be carefully examined, there can be found along the sides of the body a series of openings (Fig. 85). These are the openings through which Fig. 85. — Side-view of Locust with wings removed. the air passes into the respiratory system and are termed spiracles (spir'a-cles). Fig. 84.— Nervous system of Corydalis. (After Leidy.) 74 THE STUDY OF INSECTS. The number of spiracles varies greatly in different insects. There is, however, never more than one pair on a single segment of the body. They do not occur on the head, but are borne by each of the thoracic segments, and by the first eight abdominal segments. Thus there are eleven segments that may bear spiracles, but they are always lacking on some one or more of these. These spiracles are either simple openings into the respiratory system, or are provided with valves, sieves, or fringes of hair for the exclusion of dirt. They lead into a system of air-tubes termed tra¬ chea (tra'che-se). The accompanying figures will indicate the distri¬ bution of the main trunks of these tracheae in a cockroach (Figs. 86 and Fig. 86. — Tracheal system of Cockroach. Fig. 87. — Tracheal system of Cockroach. The dorsal integument removed and the The alimentary canal removed to show alimentary canal in place. (After Miall the ventral tracheal communications, and Denny.) (After Miall and Denny.) 87). There is a short trunk arising from each spiracle ; these are all connected together by a large longitudinal trunk on each side of the body, and by numerous transverse trunks. From these large tracheas there arise a great number of smaller ones, not shown in the figures, which branch and subdivide, and extend to all parts of the body. When one dissects an insect the viscera are found to be connected together by the ramifications of these tracheae, so that in order to remove any organ it is necessary to cut some of them. The smaller branches of the tracheae are exceedingly minute, and are intimately associated with the various tissues. By means of these fine tracheal trunks the air is carried to the tissues ; hence the blood plays a much smaller part in respiration than it does in the Vertebrates. Although insects are, strictly speaking, air-breathing animals, many of them, as is well known, live in the water. The study of the ways in which aquatic insects breathe is a very interesting one ; it HEXAPODA. 7 5 presents to us many wonderful modifications of structure. Some of the more common of these are described in subsequent pages of this book ; in this place we can only make a few generalizations. The various modes of respiration of aquatic insects may be classi¬ fied under two heads : first, those in which the insects obtain air from above the surface of the water; second, those in which the insects breathe the air that is mechanically mixed with the water. With many aquatic insects the spiracles open beneath the wings, which are folded upon the abdomen. The insect, by coming to the surface of the water and lifting the tip of its wings, forms a cavity be¬ neath them, into which the air rushes. The insect can then swim through the water, carrying this air with it in a position where it can be respired. When the air becomes impure, the insect rises to the surface, forces out the air from beneath its wings, and takes in a new supply. Water-beetles and aquatic bugs afford familiar examples of this mode of respiration. Some insects are provided with long tubes connected with their spiracles, by means of which they can draw their supply of air from above the surface of the water while they crawl upon the bottom of shallow ponds. Our most common illustrations of this are bugs of the family Nepidce\ but the most remarkable development of this kind is exhibited by certain Dipterous larvae of the family Syrphidce , known as Rat-tailed Maggots. Although there are many insects that live in the water and draw their supply of air from above it, the greater number of aquatic insects breathe, as do fishes, the air that is mixed with the water. This is accomplished by organs known as tracheal gills . These are hair-like or more or less plate-like expansions of the body- wall, abundantly supplied with tracheae (Fig. 88). These tracheae divide and subdivide, and their terminationsor fine branches are separated from the water that bathes the organ only by its thin walls. In this way the air contained in the tracheae is separated from the air in the water only by a delicate membrane, which admits of the transfer of gases between them. It win be observed that the difference between a tracheal gill and a true gill (as of fishes, Crustacea, etc.) is that the true gill is supplied with vessels containing bloody which is purified by being brought in contact with the air in the water, while the tracheal gill is supplied with tracheae containing air to be purified. Tracheal gills are usually borne by the abdomen, some¬ times by the thorax, and in case of one genus of Stone-flies by the Fig. 88.— Tracheal pill of Agrion. 76 THE STUDY OF INSECTS head. They pertain almost exclusively to the immature stages of insects ; but Stone-flies of the genus Pteronarcys retain them through¬ out their existence. Tracheal gills vary greatly in form; in Corydalis they are hair-like, and occur in tufts near the lateral margins of the abdominal seg¬ ments; in the Cadd ice-worms they are thread-like, more or less branched, and irregularly distributed over the surface of the abdo¬ men ; and in certain Dragon-flies they are in the form of large plate¬ like caudal appendages. (Fig. 88.) The Reproductive Organs. — The reproductive organs are situated in the abdomen, as represented in Figure 80. There is a set on each side of the body ; but the two sets usually open by a common tube near the caudal end of the body. In the May-flies and in the Ear¬ wigs, however, the reproductive organs of each side have a distinct opening. Thus May-flies are often found with two bunches of eggs projecting from the caudal end of the body. All insects are developed from eggs ; but there are some appar¬ ent exceptions. Thus many flies retain their eggs until after they are hatched, if a proper place for laying them is not found earlier; and in some flies (the Pupipara) the young attain a considerable de¬ velopment before they are born. In the Plant-lice {Aphid idee) there is a remarkable alternation of reproduction by budding with the sexual reproduction. This is described more fully in the account of that family. The Orders of the Hexapoda. ( For advanced students.) The Class Hexapoda, or Insects, is divided in this work into nine¬ teen orders. This number is somewhat greater than what has been commonly adopted heretofore. But we believe that in the earlier classifications forms were brought together in the same order that are not closely related, and that consequently the present classifica¬ tion represents better the true relationship of the groups of insects. There has been some hesitation on the part of many entomolo¬ gists in adopting this division of certain of the old orders, merely for the reason that they felt that the old classification was simpler. But we do not share in this feeling. It seems to us that it is easier for the student to learn the characters of a large number of well-defined groups than it is to learn those of a smaller number of vaguely- defined groups. HEXAPODA . 77 In arranging the orders in a linear series, as must be done in a book, it is impossible to indicate in a satisfactory way either the rela¬ tion of the orders to each other or the relative rank of the orders. An effort is made to place near together closely allied orders, and to treat first those that are more simple or primitive or generalized in structure, and last those that are more specialized. But this plan could be fully carried out only by having several parallel columns on the pages of the book, each representing a distinct line of descent, an arrangement which, to say the least, is impracticable. What has been done in this work is to place first the Thysanura, which is doubtless the most primitive order. Then follow first the orders that undergo an incomplete metamorphosis, and last, those that undergo a complete metamorphosis. Within these two groups of orders those with biting mouth-parts are placed first, and these are followed by those with sucking mouth-parts, except that in the second group the Coleoptera and Hymenoptera are placed last for want of a better position. We do not intend to indicate by this that these two orders are closely related, or that they are more specialized than the Diptera. In fact, with regard to at least five of the orders of insects (Hemip- tera, Lepidoptera, Diptera, Coleoptera, and Hymenoptera), it seems idle to us to discuss which is the more highly specialized. Each has been specialized in a direction peculiar to itself ; and to attempt to describe which is the “highest " seems as futile as the discussion by children of the question : “ Which is better, sugar or salt? ” We give below a table for use in classifying specimens. This table is merely intended to aid the student in determining to which of the orders a specimen that he is examining belongs. No effort has been made to indicate in the table the relation of the orders to each other. TABLE FOR DETERMINING THE ORDERS OF HEXAPODA.* ( This table includes only adult insects.) A. Wingless or with rudimentary wings. B. Mandibles and maxillae retracted within the cavity of the head so that only their apices are visible, p. 82 . Thysanura. BB. Mandibles and maxillae more or less prominent and fitted for biting. (See BBB also.) C. Head with long, trunk-like beak. ( Boreus .) p. 184. Mecoptera. * See note at bottom of p. 10. 7» THE STUDY OF INSECTS . CC. Head not prolonged into a trunk. D. Louse-like insects of small size ; body less than one-sixth inch in length. E. Antennae with not more than five segments. (Bird-lice.) p. ioo . Mallophaga. EE. Antennae with many segments. (Book-lice.) p. 98. CORRODENTIA. DD. Insects of various forms, but not louse-like, and, except in the case of some ants, with the body more than one-sixth inch in length. E. Abdomen with short, conical, compressed, many-jointed caudal appendages. ( Cockroaches .) p. 104...ORTHOPTERA. EE. Abdomen without jointed caudal appendages. F. Legs fitted for jumping. {Wingless Locusts, Grasshop¬ pers, and Crickets.) p. 104 . ORTHOPTERA. FF. Legs fitted for running, G. Abdomen broadly joined to thorax. H. Body linear. {Walking-sticks.) p. 104. ORTHOPTERA. HH. Body white and somewhat ant-like in form. ( Termes .) p. 95 . ISOPTERA. HHH. Body neither linear nor ant-like in form. ( Wingless Fire fly et al.) p. 494 . COLEOPTERA. GG. Base of abdomen strongly constricted. {Ants et al.) p. 599 . * . Hymenoptera. BBB. Mouth-parts formed for sucking. C. Small abnormal insects in which the body is either scale-like or gall-like in form, or grub-like and clothed with wax. The waxy covering may be in the form of powder, of large tufts or plates, of a continuous layer, or of a thin scale, beneath which the insect lives. {Cocci dee.) p. 121 . Hemiptera. CC. Body more or less covered with minute scales, or with thick long hairs. Prothorax not free {i.e., closely united with the mesothorax). Mouth-parts usually consisting of a long “tongue” rolled beneath the head. p. 191 . Lepidoptera. CCC. Body naked, or with isolated or bristle like hairs. D. Prothorax not well developed, inconspicuous or invisible from above. Tarsi five-jointed. Mouth-parts developed into an unjointed trunk; palpi present, p. 413. . . . Diptera. DD. Prothorax well developed. E. Body strongly compressed ; tarsi five-jointed. {Fleas.) p. 49° . Siphon aptera. HEXAPODA . 79 EE. Body not compressed ; tarsi one-, two , or three-jointed. F. Last joint of tarsi bladder-like or hoof-like in form and without claws ; mouth-parts forming a triangular, un¬ jointed beak; palpi present, p. 119 . Physopoda. FF. Last joint of tarsi not bladder-like, and furnished with one or two claws ; mouth-parts forming a slender, usually jointed beak; palpi apparently wanting, p. 121. Hemiptera. A A. Winged. (The wing-covers, efy/rp, of beetles and of earwigs are wings.) B. With two wings. C. Wings horny, leathery, or parchment-like. D. Mouth-parts formed for sucking. Wings leathery, short¬ ened, or membranous at the tip. p. 121 . Hemiptera. DD. Mouth-parts formed for biting. Jaws distinct. E. Wings horny, without veins. Hind legs not fitted for jumping, p. 494 . . Coleoptera. EE. Wings parchment-like, with a network of veins. Hind legs fitted for jumping, p. 104 . ORTHOPTERA. CC. Wings membranous. D. Abdomen with caudal filaments. Mouth-parts rudimentary. E. Halteres wanting, p. 86 . Ephemerida. EE. Halteres present (males of Coccidce). p, 12 1. Hemiptera. DD. Abdomen without caudal filaments. Halteres in place of second wings. Mouth-parts formed for sucking, p. 413. Dipt era. BB. With four wings. C. The two pairs of wings unlike in structure. D. Front wings leathery at base, and membranous at tip, often overlapping. Mouth-parts formed for sucking, p.121. Hemiptera. DD. Front wings of same texture throughout. E. Front wings horny or leathery, being veinless wing- covers. (. Elytra .) F. Abdomen with caudal appendages in form of movable forceps, p. 102 . Euplexoptera. FF. Abdomen without forcep-like appendages, p. 494. Coleoptera. EE. Front wings leathery or parchment-like, with a network of veins. F. Under wings not folded. Mouth-parts formed for suck¬ ing. p. 121 . Hemiptera. 8o THE STUDY OF INSECTS. FF. Under wings folded lengthwise. Mouth-parts formed for biting, p.104 . Orthoptera. CC. The two pairs of wings similar, membranous. D. Last joint of tarsi bladder-like or hoof-like in form and without claws, p. 1 19 . . Ph ysopoda. DD. Last joint of tarsi not bladder-like. E. Wings entirely or for the greater part clothed with scales. Mouth-parts formed for sucking, p. 191.. . LEPIDOPTERA. EE. Wings naked, transparent, or thinly clothed with hairs. F. Mouth-parts arising from the hinder part of the lower surface of the head, and consisting of bristle-like organs inclosed in a jointed sheath. (Homo fit era?) p. 121. Hemiptera. FF. Mouth-parts in normal position. Mandibles not bristle-like. G. Wings net-veined, with many veins and cross-veins. H. Tarsi consisting of less than five segments. I. Antennae inconspicuous, awl-shaped, short and slender. J. First and second pairs of wings nearly tha same length ; tarsi three-jointed, p. 89. Odonata. JJ. Second pair of wings either small or wanting; tarsi four-jointed, p. 86 . Ephemerida II. Antennae usually conspicuous, setiform, filiform clavate, capitate, or pectinate. J. Tarsi two- or three-jointed. K. Second pair of wings the smaller, p. 98. Corrodentia. KK. Second pair of wings broader, or at least of the same size as the first pair. p. 93. Plecoptera. JJ. Tarsi four-jointed ; wings equal, p. 95. Isoptera. HH. Tarsi consisting of five segments. I. Abdomen with setiform, many-jointed anal fila¬ ments. ( Certain May-flies.) p. 86. Ephemerida. II. Abdomen without many-jointed anal filaments. J. Head prolonged into a trunk-like beak. p. 184 . Mecoptera. J. Head not prolonged into a beak. p. 175. Neuroptera. HEX A POD A. 8l GG. Wings with branching veins and comparatively few cross-veins, or veinless. H. Tarsi two- or three-jointed. I. Posterior wings smaller than the anterior, p. 98 . CORRODENTIA. II. Posterior wings as large as or larger than the anterior ones. (Certain Stone-flies .) p. 93. Plecoptera. HH. Tarsi four- or five-jointed. I. Abdomen with setiform, many-jointed anal fila¬ ments. (Certain May-flies .) p. 86. Ephemerida. II. Abdomen without many-jointed anal filaments. J. Prothorax horny. First wings larger than the second, naked or imperceptibly hairy. Second wings without, or with few, unusually simple, veins. Jaws (mandibles) well developed. Palpi small, p. 599 . Hymenoptera. JJ. Prothorax membranous or, at the most, parchment-like. Second wings as large as or larger than the first, folded lengthwise, with many branching veins. First wings naked or thinly clothed with hair. Jaws (mandibles) in¬ conspicuous. Palpi long. Moth-like insects, p. 186 . Trichoptera. LIST OF ORDERS OF THE HEXAPODA. Hemiptera. Neuroptera. Mecoptera. Trichoptera. Lepidoptera. Diptera. SlPHONAPTERA. Coleoptera. Hymenoptera. Thysanura. Ephemerida. Odonata. Plecoptera. Isoptera. Corrodentia. Mallophaga. Euplexoptera Orthoptera. Physopoda. 7 CHAPTER IV. Order Thysanura (Thys-a-nu'ra). Bristle-tails , Spring-tails , Fish-moths , and others . 77z^ members of this order are wingless insects which undergo no metamorphosis , the larval form being retained by the adult . The mandibles and maxillce are retracted within the cavity of the head, so that only their tips are visible ; they have , however , freedom of motion , *72/* be used for biting and chewing soft substances. True compound eyes are rarely present ; but in some genera there is a group of simple eyes on each side of the head \ The abdomen is sometimes furnished with rudimentary legs . Under stones and decayed leaves and wood, in the chinks of bark, amongmoss, in damp places, on snow or on pools, or sometimes in houses, are the members of this order to be found. They are for the most part very small insects, but sometimes they are nu¬ merous and lively enough to make up for their lack in size. They have no wings, ^-3 but they can either run very mobryidee. (Drawn by J. M. Stedman, f^St 0T jump Very far. Their under the author’s direction.) 8, labrum; . 1 „ 10, mandible; n, maxilla: 12, labium; 12 d, mouth-parts are USUally fit- labial palpus. ’ , , , . . . J ted for biting, but are very difficult to study, because they are retracted within the « 82 THYSANURA . 83 cavity of the head, and also on account of the small size of the insects. Figure 89 represents them in place in the head, and also each separately. In certain respects these insects represent a connecting- link between the other six-footed insects (Hexapoda) and the Myriapods; for many of the Thysanura have rudiments of legs on the abdomen. It is believed, therefore, that they are much like the first insects that appeared on the earth in ancient geological times. The Thysanura undergo no metamorphosis, the young resembling the adult in form. The name of the order is from two Greek words: thysanos , a tassel ; and oura , the tail. The Thysanura include two distinct types of insects; these are classed as suborders, and can be distinguished by the following table : TABLE OF THE SUBORDERS OF THE THYSANURA. A. With bristle-like and many-jointed appendages at the caudal end of the body (in a single genus these appendages are in the form of forceps, Fig. 91), and without a sucker on the ventral side of the abdomen, p. 83 . Cinura. A A. With a forked sucker on the ventral side of the first abdominal segment. Abdomen with a springing apparatus near its caudal end, or without appendages, p. 84 . Collembola. Suborder CiNURA (Ci-nu'ra). The Bristle-tails . Often the careful housekeeper sees in the ironing-basket, or upon the book-shelf where she is dusting, a flash of light like a tiny thread of quicksilver, that usually vanishes as soon as seen. If she is experienced she knows that this streak of light is a little animal, half an inch long, whose body is clothed in shining scales like those of a fish. Hence she calls it a Fish- moth. Its scientific name is Lepisma saccharina ; (Le-pis'ma sac-cha-ri'na) ; it is especially abundant in warm climates, 84 THE STUDY OF INSECTS . and often does damage to starched clothing, book-bindings, and sometimes loosens wall-paper by eating out the paste. Under a microscope the Fish-moth shows beautiful markings Fig. 90. — Lepisma sac- charina. (After Lub¬ bock.) Fig. q\.—Japvx solifugus. (After Lubbock.) appendages. on the shining scales ; and at the caudal end of the body are three long bristle-like appendages (Fig. 90), which suggest the common name Bristle-tail applied to members of this suborder. Figure 91 represents Japyx (Ja'pyx), a Bristle- tail in which the caudal appendages are in the form of horny forceps; and Figure 92 represents the lower side of Machilis (Mach'i-lis), another Bristle-tail, found under stones and loose bark; this genus has rudimentary abdominal legs as shown in the figure. Suborder Collembola (Col-lem'bo-la). The Spring-tails. In the Spring in the Northern States, on bright sunny days when it is thawing, one often sees upon the snow thou¬ sands of tiny dark specks. In other places pools of still THYSANURA. 85 water appear to be covered by a moving mass of minute grains which become more active when disturbed. These masses as well as the dark specks on snow consist of thou¬ sands of little creatures that are provided with a wonderful means of jumping. There is on the end of the body a tail-like organ that is bent under when the insect is at rest, and that reaches almost to the head ; this when suddenly straightened throws the insect high in the air and several feet away. This action is like a spring-board jump, only these little fellows always carry their spring-boards with them, and have thus won the name of Spring-tails. The species upon snow, called the Snow-flea, Achorutes nivicola (Ach-o-ru'tes ni-vic'o-la), sometimes proves a nuisance in maple sugar-bushes by get¬ ting into the sap. Through a micro¬ scope a Spring-tail appears very ab¬ surd, it has long antennae and large, dark eye-spots on the face, which, to¬ gether with the long hair that sticks forward on the head and thorax, give the creature a look of solemn n rv • rr • Fig. 93. — Papirtus fuscus. (After fierceness. Different species may Lubbock.) be found at almost any time of the year in damp places. Figure 93 represents one of these. In many forms the body is much more slender than in that figured. CHAPTER V. Order Ephemerida (Eph-e-mer'i-da). The May -flies. The members of this order have delicate membranous wings , with a fine network of veins ; the fore wings are large , and the hind wings are much smaller or wanting. The mouth- parts are rudimentary. The metamorphosis is incomplete. The name of this order is from the Greek word ephemeros , lasting but a day. It was given to these in¬ sects on account of the shortness of their lives after reaching the adult state.* The May-flies are easily dis¬ tinguished from other net-winged in¬ sects by the peculiar shape of the wings and the relative sizes of the two pairs (Fig. 94). The mouth-parts are nearly want¬ ing, as these insects eat nothing in the adult state ; the antennae are very small ; the abdomen is long, soft, and terminated by two or three many- jointed, thread-like appendages. In their metamorphoses these insects differ from all others in molting once after they have acquired wings fitted for flight. This order includes only a single family. * We have not adopted the name Plectoptera , which has been proposed for these insects, on account of its similarity to Plecoptera . 86 EPHEMERIDA. 8 7 Family EPHEMERlDiE (Eph-e-mer'i-dae). The May-flics. In river or lake towns, during the warm evenings of late spring or early summer, the electric lights or street lamps are often darkened by myriads of insects that dash against them, and the pavements are made slippery by their dead bodies which have been trampled under foot. They are not the ordi¬ nary night-flying moths : if an individual of the thousands that cling to the posts and buildings in the vicinity of the light be examined, it will prove to be a delicate creature with dainty, trembling wings and two or three long, white, thread-like organs on the end of its body ; the body itself is so transparent that the blood within can be seen pulsating. The front wings are large and finely netted, and the hind wings are small or absent (Figs. 94, 95). Fla‘ two^ngeS So fragile are these pale beings that they seem like phantoms rather than real insects. No wonder that poets have sung of them as the creatures that live only a day. It is true that their winged existence lasts often only a day or even a few hours ; but they have another life, of which the poet knows nothing. Down on the bottom of a stream, feeding on mud, water-plants, or other small insects, lives a little nympli with delicate, fringed gills along its sides and two or three long, many-jointed, and often feathery appendages on the end of the body (Fig. 96). It has strong legs and can both walk and swim. After about the ninth molt there may be twenty molts in all — there appear on its thorax four little sacs which are the beginnings of wings ; with each molt these grow larger, until finally the last skin of the water-nymph is shed, and gills and mouth-parts are all left behind, and the insect comes forth, a winged May-fly. But there is still o?May-Xy.P another change to be undergone. The insect has not yet reached the adult state. After flying a 88 THE STUD Y OF INSECTS. short distance it alights and sheds its skin again, a thin layer coming off from all parts of its body, even from its wings. After this the delicate creature is more fragile than before. It now has but one duty to perform in its brief life in the air, and that is to lay its eggs. These are sometimes laid on the surface of the water, and sometimes the mother wraps her wings about her like a diving-bell and goes down into the water and deposits her eggs on stones. The life of the nymph is from one to three years, according to the species. CHAPTER VI. Order Odonata (Od-o-na'ta). The Drago?i-Jlies a?id the Damsel- flies. The members of this order have four membranous wings , which are finely ?ietted with veins ; the hind wings are as large or larger than the fore wings ; and each wing has near the middle of the front margin a joint-like structure , the nodus. The mouth-parts are formed for biting . The metamorphosis is incomplete . The name of this order is evidently from the Greek word odouSy a tooth ; but the reason for applying it to these insects is obscure. The Odonata are easily recognized by the form of their wings, which are long and narrow ; and possess near the middle of the front margin of each a little notch and a strong cross-vein. This structure resembles in appearance a joint, and is consequently named the nodus . The mouth-parts are fitted for biting, these insects be¬ ing carnivorous and voracious feeders in the adult state. Both the upper lip and the lower lip are large, and the two nearly enclose the jaws when at rest. The nymphs are all aquatic, and can be easily recog¬ nized by the form of the labium, which is long and jointed, and when extended reaches far out; it is armed with pow¬ erful hooks with which to seize their prey. The terminal portion is broad ; and when the lip is folded back in the position of rest, it presents an appearance which has sug¬ gested for it the term mask. Sg 9o THE STUDY OF INSECTS . Like the adults, the nymphs are strictly carnivorous. They feed on a great variety of insects; and they also destroy worms, crustaceans, fish-fry, and tadpoles. There are two quite distinct types of insects included in this order; these represent two suborders. Suborder Anisoptera (An-is-op'te-ra). The Dragon-flies . The dragon-flies are easily distinguished by the relative size of the two pairs of wings, and by the attitude of the wings when at rest (Fig. 97). The hind wings are larger Fig. 97. — A dragon-fly. than the fore wings and are of a somewhat different shape; the name Anisoptera, from the Greek anisos , unequal, and pteron, wing, refers to this fact. But the most striking characteristic is the fact that the wings are extended horizontally when at rest. Darning-needles, devirs-needles, snake-doctors, spin¬ dles, and dragon-flies are some of the names given to these insects which dart back and forth over streams and wet places, their rapidly moving wings throwing out gleams of metallic color as they go. Still more beautiful are they when at rest, their wings wide-spread above the abdomen, and as rigid and motionless as if made of iridescent glass; A N I SOP TER A . 91 and their great compound eyes shining like gold or pre¬ cious stones. But for all their terrible names, dragon-flies are entirely innocent of any harm to mankind. They neither sew up people’s ears, as northern children think; nor bring dead snakes to life, as colored people in the South believe; but they are very fierce enemies to their insect kindred. Their long, narrow, closely netted wings are strong, carrying them swiftly ; and their jaws are powerful, and their appetites good ; so it is an unfortunate insect that falls in their way. The fact that they destroy mosquitoes has attracted much attention of late ; but they feed upon a great variety of insects; and the larger species habitu¬ ally eat the smaller ones. The eggs of dragon-flies are laid in water or fastened to aquatic plants. The nymphs present a striking peculiarity of the respiratory system ; very large tra¬ cheae extend to the rectum, and their branches penetrate its wall and end in a complicated series of tracheal gills in the cavity of the rectum. The insect alternately draws water into this cavity and expels it; and thus the air in these trachea? is purified. This process also nympfrif^goTfly helps the insect in swimming, for the water may be expelled with such force that the whole body is sent forward. The full-grown nymph leaves the water to undergo its last molt ; and the exuviae are often found clinging to objects near the water (Fig. 98). Suborder Zygoptera (Zy-gop'te-ra). The Damsel- flies. The damsel-flies differ from the dragon-flies in that the two pairs of wings are similar in form and are either folded 92 THE STUDY OF INSECTS . parallel with the abdomen when at rest (Fig. 99) or are up- tilted. The head is transverse, each eye being borne by a lateral prolongation of the head. The females possess an 1 — nympa oi a no. ioi.— damsel-fly. Tracheal gill of nymph of damsel-fly. ovipositor by means of which the eggs are placed in the stems of aquatic plants, sometimes beneath the surface of the water. The name of the suborder is from the Greek zygon , yoke, and pteron , wing; it probably refers to the fact that the wings are brought together when at rest. Unlike the dragon-flies, the damsel-flies are compara¬ tively feeble in their flight. They are found near the margins of streams and ponds, in which the nymph stages are passed. The nymphs of damsel-flies (Fig. 100) possess leaflike tracheal gills at the caudal end of the body. One of these is represented greatly enlarged by Fig. 101. CHAPTER VII. Order PLECOPTERA (Ple-cop'te-ra). The Stone-flies. The members of this order have four membranous wings , with comparatively few or with many cross-veins ; the hind wings are much larger than the fore wings , and are folded in plaits and lie upon the abdomen when at rest. The mouth- parts are of the biting type of structure , but are frequently poorly developed. The metamorphosis is incomplete. The name of this order is from two Greek words : plecos , plaited ; and pteron, a wing. It refers to the way in which the hind wings are folded when at rest. Although the mouth-parts are of the biting type of struc¬ ture, the mandibles are often small, flat, and membranous, and evidently of little use. It is probable that as a rule the adults eat but little. The antenna: are long, tapering, and many-jointed ; and in most species the caudal end of the abdomen is furnished with two many-jointed bristles. The nymphs are aquatic. This order includes only a single family- Family Perlid^: (Per'li-dae). The Stone-flies. Those boys fond of fishing know that a good place to find bait is under stones in streams. And doubtless they have often observed that in the swiftest portion of the stream the turned-over stones have clinging to the lower surface 93 94 THE STUDY OF INSECTS. flat creatures from one-half inch or less to one and one half inches in length. They cling so closely and are so nearly the color of the stone that they look almost like fossils. Their antennae and caudal bristles and three legs on each side extend out like the rays of a star ; the six soft clumps of white hair-like gills, one behind each leg, alone show that they are not engraved upon the stone (Fig. 102). These insects are the nymphs of the stone-flies, and are the favorite- food of fishes, especially of brook trout. If a nymph is fortunate enough to escape the fate of being a luncheon for fish, when it is full-grown it crawls forth from the water and Fig. 102. — Nymph of Stone- Fig. 103 .—Pteronarcys regalis. fly, Acroneura. transforms to a gray or greenish fly, with slender, closely veined fore wings and wide, delicate hind wings (Fig. 103). The cast nymph-skins are common objects on the banks of the streams which these insects inhabit. Several of the smaller species of the stone-flies appear in the winged state upon snow in early spring, and often find their way into houses. CHAPTER VIII. Order ISOPTERA (I-sop'te-ra). The Termites or White-ants. The members of this order are social insects. Each species consists of several distinct castes, of which only the “ Kings ” and the “ Queens ” are winged. These have four long, nar¬ row wings, which are somewhat leathery in structure, and which are furnished with numerous but more or less indistinct veins. The two pairs of wings are similar in form and struc¬ ture, and are laid flat upon the back when not in use. The mouth-parts are formed for biting. The metamorphosis is in¬ complete. The name of this order is from two Greek words : isos, equal ; and pteron, a wing. It refers to the fact that the two pairs of wings are similar in form and structure. The wings of the Termites (Ter'mites), although really broad when compared to the size of the body, appear narrow on account of their great length, being in many cases more than twice as long as the entire body. The order includes only a single family. Family Termitid,e (Ter-mit'i-das). The Termites or White-ants. These interesting insects are not Ants, nor at all related to them ; but they have been thus called because they have certain social habits that are similar to those of true Ants. They are more abundant in the tropics than here; and 95 96 THE STUDY OF INSECTS , Fig. 104. — Ter tries Jlapives , worker. Fig. 105. — Ter met Jlavipes , soldier. there build nests or mounds sometimes twelve feet high, or make roundish nests several feet thick on trees. Our Northern species ( Termes Jlavipes) lives in old logs and stumps, or under stones in the ground. A remarkable thing about the White-ants is the way they are divided into classes, each class fitted to do a certain work for the colony. First, there is the class of workers (Fig. 104), which is constituted of both sexes : they are wingless, and of a dirty-white color, and while they resemble true ants somewhat, their waists are thicker. Their business is to bring food for everybody, feed and bring up the young termites, and build nests. Second, there is the class called soldiers (Fig. 105) : these too are of both sexes and wingless, and look somewhat like the workers, only their heads are tremendous in size, being often nearly as long as the rest of the body, and their jaws are large and powerful. Third, is the royal class called kings and queens . It would have been better to have called them fathers and mothers, as they are the parents of the colony, and do not rule it. This class when grown have wings which lie flat upon the back when at rest, and may be twice as long as the body. In May or June in our common species this class swarms forth from all the nests of the neighborhood. After a flight of some distance the wings are shed, and a king chooses some queen near him and proposes that they start a king¬ dom of their own. But like mortal kings and queens they cannot reign unless a kingdom is found for them, and so millions of these royal pairs die because they have no sub¬ jects. But sometimes a fortunate couple is discovered by some termite workers, who at once take possession of the ISOPTERA. 97 wanderers and provide them with food, and with shelter in the shape of a large circular shallow cell. In this they are really imprisoned, but are well cared for. Soon the queen or mother begins to develop eggs, and her body grows enormously. Finally, it is nothing but a huge sac filled with eggs, looking more like a potato than anything else, and is sometimes six or seven inches long (Fig. 106). Of course the poor queen cannot move herself in the least, and if she were not fed would soon starve ; but her king remains devoted to her, and her ladies and gentlemen in waiting do their best to make her comfortable: they carry away the eggs to other chambers as soon as they are laid, then care for the eggs, and feed the little ones when they are hatched. Fic Io6._Quee[1 white. The young termites are active, and re- ant> T*rmes gtivus. semble the adult in form. If a nest becomes queenless, and the workers are unable to procure a queen, there are de¬ veloped in the nest wingless sexual individuals, which are termed complemental males and females. But as each com- plemental female lays only a few eggs, it requires several to take the place of a real queen. All White-ants are miners, and avoid the light. They build covered-ways wherever they wish to go. In hot countries they are a terrible pest, as they feed upon wood, and actually destroy buildings and furniture and libraries. They leave merely the outside portion of what they feed upon ; and they have been known to enter a table through the bottom of the legs and to eat all the inner portions so that a slight weight crushed it to the floor. In Florida they do damage to orange and other trees by girdling them below the surface of the ground. 8 \ CHAPTER IX. Order CORRODENTIA (Cor-ro-den'ti-a). The Psocids (Psocids) and the Book-lice . The winged members of this order have four membranous wings , with the veins prominent , but with comparatively few cress veins ; the fore wings are larger than the hind wings; and both pairs when not in use are placed roof-like over the body , being almost vertical , and not folded in plaits . The mouth-parts are formed for biting . The metamorphosis is in¬ complete. The name of this order is from the Latin corrodere , to gnaw, and refers to the gnawing habits of these insects. The wings, especially the fore wings, are often smoky in color or fig. io7.— Psocus vtnosus. variegated. The arrangement of the veins of the wings (Fig. 107) differs in a striking manner from that of any other biting insect. The order includes two families, but representatives of only one of them occur in the United States. Family PSOCIDS (Psoc'i-dae). The Psocids (Pso'cids) and the Book-lice. Books may be old and out of date from our standpoint, but still be of vital importance to others. Take down from the shelf a time-yellowed book and open its neglected leaves 98 CORRODEN TIA. 99 and watch the pale tiny creatures that scurry across its pages; examine one of them with a lens, look well at his alert, knowing, black eyes, and we are sure you will believe that he is in search of real literature, and not merely a feeder upon paper, as we are taught. Anyway, scientists have con¬ cluded that these insects look wise enough to bear the name Atropos divinatoria (At'ro-pos di-vin-a-to'ri-a), or the Divining Atropos (Fig. 108). They are, however, more commonly called simply book-lice. Some members of the family Psocidae do not live in books, but feed upon lichens that are found on the trunks of trees and on fences, often a great number being grouped together. a Ziook-iouse. Many of these have wings, and look like plant-lice (Fig. 107). The eggs are laid in heaps on leaves and branches, and are covered with a tissue of threads ; for the Psocids have the power of spinning silk similar to that spun by spiders. CHAPTER X. Order Mallophaga (Mal-loph'a-ga). The Bird-lice. The members of this order are wingless parasitic insects , with biting mouth-parts. Their metamorphosis is incomplete. The name of the order is from two Greek words : mallos , wool ; and phageiny to eat. Although some species infest sheep and goats, feeding upon their wool, by far the greater number live among the feathers of birds. It is due to this fact that the common name Bird-lice is applied to the entire group. The order includes several families; but we will not take the space to define them. The Bird-lice are well known to most people that have pet birds or who keep poultry. They differ from the true Lice in having biting mouth-parts, and in feeding upon either feathers, hair, or the skin ; while the true Lice have sucking mouth-parts and feed upon blood. It is to free themselves from these pests that hens wallow in the dust. When poultry are kept in closed houses they should be provided with a “ dust-bath.” All poultry-houses should be cleaned at least twice a year, and the old straw burned. Sprinkling powdered sulphur in the nests and oiling the perches with kerosene will tend to keep the pests in check. If a poultry-house becomes badly infested, it should be cleaned thoroughly, and every part whitewashed ; and the poultry should be dusted with Buhach or Persian insect powder (Byrethrum). ioo MALLOPHAGA IOI Fig. 109 represents Goniodes sty lifer (Gon-i-o'des styl'r fer), a species which infests the turkey; and Fig. no, Fig. 109. — Goniodes sty lifer. (From Law.) Fig. 1 10. — Trichodectes scalar is, (From Law.) Trichodectes scalaris (Trich-o-dec'tes sca-la'ris), a species infesting the ox. CHAPTER XI. Order Euplexoptera (Eu-plex-op'te-ra). The Earwigs. The members of this order have usually four wings ; the first pair of which are leathery , very small , without veins , and when at rest meet in a straight line on the back ; the second pair are large , with radiating veins , and when at rest are folded both lengthwise and crossivise. The mouth-parts are formed for biting. The caudal end of the body is furnished with a pair of appendages which resemble forceps. The meta¬ morphosis is incomplete . The name of the order is from three Greek words : eut well ; pleko , to fold ; and pteron , wing. The word is not well formed, but it cannot now be changed. It refers to the unusual folding of the hind wings. This order is termed the Dermaptera by many entomologists, but this name was first applied to certain other insects, and so should not be used for these. The fore wings of these insects resemble the wing-covers of beetles, and like them differ greatly from the usual form. The hind wings are very different from those of any other insects. Figure 1 1 1 represents one of these; they are furnished with radi¬ ating veins, which extends from a point some distance from the base of the wings. When the wing is not in use that part over which these Fig. 1 1 1. —Wing of Earwig. veins extend is folded in plaits like a fan, after which the wing is folded twice crosswise. Al- 102 E UPLEXOP TER A. 103 though these insects bear some resemblance to beetles, they differ from them markedly in having an incomplete meta¬ morphosis. The order includes only a single family. Family Forficulid^e (For-fi-cu'li-das). The Earwigs . These are long and narrow insects, resembling rove* beetles in the form of the body and in the shortness of the wing - covers, but easily distinguished by having a pair of forceps at the end of the body (Fig. 1 12). The common name, earwig^ has reference to a widely spread fancy that these insects creep into the ears of sleeping persons. The earwigs are rare in the North¬ eastern United States, but are more often found in the South and on the Pacific coast. In Europe they are com¬ mon, and are often troublesome pests, feeding upon the corollas of flowers, , . , , ,ii 1 . Fig. i 12.— An Earwig. fruits, and other vegetable substances. f CHAPTER XII. Order ORTHOPTERA ( Or-thop' te-ra ). Cockroaches , Crickets , Grasshoppers, and others . The members of this order have four wings : the first pair are thickened , and overlap when at rest ; the second pair are thinner , and are folded in plaits like a fan . The mouth-parts are formed for biting . The metamorphosis is incomplete . The order Orthoptera includes some of the very common and best-known insects. The most familiar representatives are those named above. Although the song of the Katydid and the chirp of crickets are most often associated with recollections of pleas¬ ant evenings spent in the country, we cannot forget that to members of this order are due some of the most terrible insect scourges man has known. The devastations caused by great swarms of migratory locusts are not only matters of historical record, but are too painfully known to many of our own generation in the Western States. With the exception of a single family ( Mantidce ), the members of this order are, as a rule, injurious to vegetation ; and many species are quite apt to multiply to such an extent that their destruction of vegetation becomes serious. The name of the order is from two Greek words: orthos , straight ; and pteron , a wing. It refers to the longitudinal folding of the hind wings. In the Orthoptera the two pairs of wings differ in struc¬ ture. The fore wings are parchment-like, forming covers for the more delicate hind wings. These wing-covers have re- 104 ORTHOPTERA. 105 ceived the special name tegmina (teg'mi-na); they are furnished with a fine network of veins, and overlap at the tip at least. There are many species in which the wings are rudimentary, even in the adult state. Such adults resemble nymphs ; but in the case of the jumping Orthoptera, where this peculiar- ity most often occurs, nymphs can be distinguished by the fact that the rudimentary hind wings are outside of the fore wings, instead of beneath them, as in the adult state. This order includes only six families. We are able, there¬ fore, to discuss all of them in this work. The following synopsis will aid the student in fixing in his mind the more important characteristics of each family. SYNOPSIS OF THE FAMILIES OF THE ORTHOPTERA. The Running Orthoptera.— The body is oval when seen from above, and is very flat; the three pairs of legs are similar in form ; the insects run rapidly, p. 106 . Blattida:. The Grasping Orthoptera.— The prothorax is very long and slender ; the first pair of legs are very different from the others. and are fitted for grasping, p. 106 . .Mantidas. The Walking Orthoptera.— The body is very long and slender; the three pairs of legs are similar in form, and are also very long and slender ; the insects walk slowly, p. 108. . . . Phasmida:. The Jumping Orthoptera.— The hind legs are very much stouter or very much longer, or both stouter and longer, than the middle pair, being fitted for jumping. This group includes three families : The Short-hor?ied Grasshoppers , or Locusts. — The antennae are shorter than the body. The ovipositor of the female is short and composed of four separate plates. The tarsi are three-jointed. p. . . . The Long-horned Grasshoppers.— The antennae are very slender and longer than the body. (This is also true of the crickets.) The ovipositor is sword-shaped. The tarsi are four-jointed. p . . LOCUSTIDiE. The Crickets,— The antennae, like those of the long-horned grass¬ hoppers, are very slender and longer than the body, except in the mole-crickets. The ovipositor is spear-shaped when exerted. The tarsi are three-jointed, p. 115 . GRYLLiDiE. io6 THE STUDY OF INSECTS. Family Blattid^E (Blat'ti-dae). The Cockroaches . After every one is in bed at night and all is quiet in the kitchen where there are water-pipes, often a throng of little creatures come forth from hiding-places and, like brownies, take possession of everything. They race around every where, trying to find something to eat ; they do not care much whether it is raw or cooked, but will devour almost anything that comes in reach of their greedy jaws. They eat book-bindings and bedbugs, if they find them, with equal alacrity ; and sometimes they get bold enough to appear in broad daylight. The little, pale brown rascal called the Croton-bug, which came to us from Europe and infests the vicinity of the pipes of the water systems of many of our cities, is es¬ pecially bold and impu¬ dent (Fig. 1 13). In fact, in the North our native cockroaches are mostly F>g. 1x3. — The Croton-bug. Fig. i i 5.— Ootheca of a Cock¬ roach. Fig. 114. — A Wing¬ less Cockroach. respectable, well-behaved insects, living in fields and forests under sticks and stones, the emigrant cockroaches being the offenders. Many cockroaches are wingless (Fig. 114). The eggs of a cockroach are laid, all at once, enclosed in a sort of pod which is more or less bean-shaped (Fig. 115). Thorough and frequent dusting with insect-powder in the cracks about the kitchen will rid a house of these pests. Family Mantid^E (Man'ti-dae). The Praying Mantes , or Mule-killers . Certainly they are pious-looking fellows, with their front legs clasped together in front of their meek, alert faces, and ORTHOPTERA . 107 it is no wonder that they are called Praying Mantes. But the only prayer that could ever enter the mind of a Mantis Fig. xi6. — Phasmomantis Carolina. would be that some unwary insect might come near enough for him to grab it with his hypo¬ critical claws, and so get a meal. Devil-horses* rear-horses, and camel-crickets are other names applied to these insects, because of the long, slender prothorax which makes them look like tiny giraffes. They are also called mule-killers* from the absurd superstition that the dark-col¬ ored saliva they eject from their mouths is fatal ® to the mule. But they are absolutely harmless to both man and beast. They are mostly tropical insects, and often have wings that resemble the leaves of trees. Our common species, Phasmo - mantis Carolina (Phas-mo-man'tis) (Fig. 116), is confined to the Southern States. The eggs are laid in masses and overlaid with a hard covering of silk; the top of the masses having the appearance of be¬ ing braided (Fig. 117). Fig. 117. — Epp-mass of a Ma antis. 108 THE STUDY OF INSECTS. Family PHASMlDAi (Phas'mi-dae). The Walking-sticks. The rambler in forests is often surprised to discover that a part of the casually-plucked branch in his hand is alive. A certain twig that was stiff and motionless sud¬ denly, when disturbed, walks off on long slender legs, as awkwardly as if it had never tried to walk before. Strange and uncanny creatures are these walking-sticks with their long pointed bodies and with legs colored and looking exactly like twigs and leaf-peti¬ oles. In the tropics their resem¬ blance to foliage is made more perfect by wings which are veined like leaves. In the Northern States we have only one common species, Diapheromera femorata , (Di-aph-e- rom'e-ra fem-o-ra'ta), and that is wingless (Fig. 118). Walking- sticks feed upon foliage. Their eggs, which are large, are dropped on the ground under the trees by Fig. 118. — a Walking-stick. the mother, who trusts entirely to fate to preserve them. Family ACRIDIDA2 (A-crid'i-dse). Locusts, or Short-horned Grasshoppers . Every country lad is familiar with the appearance of grasshoppers. But there are many kinds of these insects, representing at least two distinct families. The family Acrididae, or Locusts, includes those grasshoppers in which ORTHOPTERA. IOg the antennae, are shorter than the body, and in which the ovipositor of the female is short and made up of four sepa¬ rate plates (Fig. 119). The tarsi are three-jointed; and on Fig. 119. — Side view of Locust with wings removed. each side of the first segment of the abdomen there is a cir¬ cular plate which is believed to be an ear. It is to these insects that the term locust is properly ap¬ plied. For the locusts of which we read in the Bible, and in other books published in the older countries, are members of this family. Unfortunately in the United States the term locust has been applied to the Periodical Cicada, a member of the order Hemiptera, described later. And, what is more unfortunate, the scientific name Locustidae was given long ago to the next family and cannot now be changed. It should be remembered, therefore, that the locusts do not belong to the Locustidae. Locusts lay their eggs in oval masses and cover them with a tough substance. Some species lay their eggs in the ground. The female makes a hole in the ground with her ovipositor, which is a good digging-tool. Some species even make holes in fence-rails, logs, and stumps; then, after the eggs are laid, the hole is covered up with a plug of gummy materials. There is but one generation a year, and in most cases the winter is passed in the egg-state. This family is of great economic importance, as the members of it usually appear in great numbers in every region where plants grow, and often do much damage. The males of many locusts are able to produce sounds. This is done in two ways: First, certain species rub the inner surface of the hind femora, upon which there is a row of minute spines, against the outer surface of the wing-covers. no THE STUDY OF INSECTS. The legged In this case each wing-cover serves as a fiddle, and each hind¬ leg as a fiddle-bow. Second, other species rub together the upper surface of the front edge of the hind-wings and the under surface of the wing-covers. This is done while the locust is flying, and the result is a crackling sound. There are very many species of locusts in the United States. We have space to refer to only a few here. most familiar member of the family is the Red- Locust, Melanopliis femur-rubrum (Me-lan'o-plus) (Fig. 1 20). It is more abun. dant than any other species throughout the United States, except in the high dry lands of the central part of the Fl°. wo.—Meltinoplusfemur-rubrum. continent> Here the Rocky Mountain Locust, Melanopliis spretus , abounds. This spe¬ cies closely resembles the red-legged locust, except that it has longer wings. It is this insect that sometimes migrates into the lower and more fertile regions of the Mississippi Valley and does such great damage. It will be remembered that at one time it almost produced a famine in Kansas and the neighboring States. Fortunately the young of this insect hatched in the low regions are not healthy, and die before reaching maturity. Consequently the plagues caused by the emigration of this insect are of short duration. There are several other species of Melanoplus common in this country, but they can be distinguished only by very careful study. The Clouded Locust, Encoptolophus sordidus (En-cop-tol'- o-phus sor'di-dus) (Fig. 121), is very common in the Eastern United States during the autumn. It abounds in meadows and pastures, and attracts attention by the crackling sound made by the males during flight. Its F|C- 121 -—Encoptolophus sordidus, color is dirty brown, mottled with darker spots. ORTHOPTERA . Ill The Carolina Locust, Dissosteira Carolina, (Dis-sos-tei'ra), is common throughout the United States and Canada, and at the North is our largest species. It lives in roads and on bare places, and its color matches the soil on which it lives. It is usually pale yellowish or reddish-brown or slate color, with small dusky spots. The hind wings are black, with a broad yellow edge. It measures from one inch and a half to nearly two inches in length. The Sprinkled Locust, Chrysochraon conspersum (Chry- soch'ra-on con-sper'sum) (Fig. 122), is a common species. Here the wings are a little shorter than the abdomen in the males, and much shorter in the females. I ft the South and in the Fig. ,22. — Chrysochraon conspersum. West we find several genera in which the body is very long and slender. Leptysma marguiicolle (Leptys'ma mar-gin-i- F.g. „3 .-L'ftyma marginicolle. col'le) (Fig. 1 23), will serve as an illustration of the form of these insects. There is a group of small locusts of which Tcttix (Fig. 124) is an example, which is remarkable for the shape of the pronotum. This projects backward like a little roof over the wings, and often extends beyond the end of the abdomen. With these insects the wing-covers are in F,G- «« --Tettu. the shape of small rough scales, the wings being protected by the large pronotum. These insects are commonly found in low, wet places, and on the borders of streams. Their colors are usually dark, and are often protective, closely resembling that of the soil upon which they occur. These locusts are very active, jumping great distances. 112 THE STUDY OF INSECTS. Family LOCUSTID.E (Lo-cus'ti-dse). The Long-hortied Grasshoppers. Any one that is in the habit of lying in the tall grass of meadows or pastures and watching the insects that can be seen there is sure to be familiar with certain green grass¬ hoppers, which attract attention by the extreme delicacy and great length of their antennae. These are our most a. common members of the Locustidae. The // M*-! antennae are much more slender than with ft the short-horned grasshoppers or locusts, and y \ much longer, exceeding the body in length. The tarsi are four-jointed. The ear-like Fig. i?5.— Let* of organs, when present, are situated near the ei?-likeOTgahn°.wing base of the fore tibiae (Fig. 125), and the ovipositor is sword-shaped. In those species of this family in which the wings are well developed we find the males provided with an elabo- Fig. 126. — Wing-cover of Male Meadow Grasshopper. Fig. 137. — Wing-cover of Female Meadow Grasshopper. rate musical apparatus by means of which they call their mates. This consists of a peculiar arrangement of the veins and cells of a portion of each wing-cover near its base. This arrangement differs in the different species ; but in each it is ORTHOPTERA . 113 such that by rubbing the wing-covers together they are made to vibrate, and thus produce the sound. Figure 126 repre¬ sents a wing-cover of the male of a common meadow grass¬ hopper, and Figure 127 that of a female of the same species. In order to facilitate the study of this family the more common representatives can be arranged in four groups : The Meadow Grasshoppers, the Katydids, the Cricket-like Grasshoppers, and the Shield-backed Grasshoppers. I. The Meadow Grasshoppers. — Under this head can be classed our most common members of the family; they abound upon grass in meadows and in moist places. Figure 128 represents one of these insects. II. The Katydids.— The chances are that he who lies awake of a midsummer night must listen whether he wishes to do so or not, to an oft-repeated, rasping song that says, “ Katy did, Katy did ; she did, she didn't,” over and over again. There is no use of wondering what Katy did or didn’t do, for no mortal will ever know. If, when the dawn comes, the listener has eyes sharp enough to discern one of these singers among the leaves of some neighboring tree, never a note of explanation will he get. The beautiful, finely- veined wings folded close over the body keep the secret hid¬ den, and the long antennas, looking like threads of living silk, will wave airily above the droll, green eyes as much as to say, 41 Wouldn't you like to know?" The katydids live only on trees, and sing only during the night. There are several species of katydids common in the United States. The Western and Southern species, called the Angular-winged Katydid, Microcentrum retinervis (Mic-ro-cen'trum ret-i'ner- vis) lays its eggs in neat rows upon leaves and branches ; the eggs are oval, and each overlaps its neighbor slightly Fig. 128 . — Xiph i d i u tti . THE STUDY OF INSECTS . 1 14 (Fig. 129). In many sections where the katydids do not occur, the song of the Snowy Tree-cricket, described later, is often mistaken for that of a Katydid. Fig. 129. — The Angular-winged Katydid and its eggs. III. The Cricket-like Grasshoppers . — These are wingless, and resemble crickets in form. The most common members of this group belong to the genus CeutJiophilus (Ceu-thoph'i-lus) (Fig. 130). These insects are found under stones and rub¬ bish, especially in woods. Fig. 130. — Ceuthofhilus. . , V ery closely allied to them are the colorless and blind Cave-crickets, Hadencecus (Had-e- nee'eus), found in caves. ORTHOP TER A. 115 IV. The Shield backed Grasshoppers. — These are also wingless, and dull-colored insects, which bear some resem¬ blance to crickets. They present, however, a queer appearance, due to the pronotum extend¬ ing backward over the rest of the thorax, like a sun-bonnet worn over Fig- Thyreonotus, . the shoulders with the back side forward. This group is repre¬ sented in the Eastern half of the United States by Thyreo- notus (Thyr-e-o-no'tus) (Fig. 131). In the regions west of the Mississippi River occur the “ Western Crickets,” belonging to the genus Anabrus (An'a-brus), and on the Pacific coast Fig. 132. — Ste nopelmntus. there are large, clumsy creatures with big heads, that live under stones and in loose soil, and are popularly known as Sand-crickets. These belong to the genus Stenopelmatus (Stcn-o-pel-ma'tus) (Fig. 132). Family Gryllid^: (Gryl'li-dae). The Crickets . The crickets differ from both families of grasshoppers in having the wing-covers flat above and bent sharply down at the edge of the body like a box-cover, instead of meeting in a ridge above the body like a roof. The antennae are long Ji6 THE STUDY OF INSECTS. and slender, like those of the Locustidae ; but the form of the ovipositor is quite different in this family, being spear- shaped, instead of sword-like. The males of the crickets have musical organs which are even more elaborate than those of the Katydids and meadow grasshoppers. Here all that part of each wing-cover that lies on the back is occupied by them. This gives the males a very different appearance from the females, the wing- covers of that sex being veined simply. During the latter part of summer and in the autumn the air is filled with the chirping of crickets. It is an interest¬ ing thing to watch one of these fiddlers calling his mate. By moving quietly in the- direction from which the sound comes, and stopping whenever the insect stops chirping, but moving on again when he renews his song, one can get near enough to see how he does it. This can be done even in the night with the aid of a lantern, as the crickets do not seem to mind lights. Figure 133 represents the musical apparatus of a cricket. Fig. 133. — Tegmina of male Gryllus. From this it will be seen that the large veins divide the wing- covers into disk-like membranous spaces. If the principal vein which extends diagonally across the base of the wing- ORTHOPTERA. II 7 cover be examined with a microscope, it will be seen to be furnished with ridges like those of a file (Fig. 133, b). On the inner margin of the wing-cover, a short distance toward the base from the end of the principal vein, there is a hardened portion which may be called the scraper. This is shown enlarged at c in the figure. Each wing-cover is there¬ fore provided with a file and a scraper. When the cricket wishes to make his call, he elevates his wing-covers at an angle of about forty-five degrees with the body ; then hold¬ ing them in such a position that the scraper of one rests upon the file of the other, he moves the wing-covers back and forth sidewise so that the file and the scraper rasp upon each other. This throws the wing-covers into vibration, and produces the call. There are comparatively few species of crickets, but they represent three quite distinct groups. These can be dis¬ tinguished as the Mole Crickets, the True Crickets, and the Tree Crickets. I. The Mole Crickets . — These are called Mole Crickets because they burrow in the ground like moles. There are species belonging to the next group, the true crickets, which burrow in the ground ; but the mole-crickets are pre-eminently burrowers. The form of the body is suited to this mode of life. The front tibiae, especially, are fitted for digging; they are greatly broadened, and shaped somewhat like hands, or the feet of a mole. Figure 134 represents one of these insects. The mole-crickets feed upon the tender roots of various plants, and where they are common they are serious pests. II. The True Crickets. — To this group belong our com¬ mon, black acquaintances that peep at us from the cracks Iltf THE STUDY OF INSECTS . in the paving, or jump across our paths when we walk in the fields. They are com¬ mon everywhere; some spe¬ cies even live in our houses. They usually feed upon plants, but are sometimes predaceous. Fig. xzs.-Gryitus abbreviate. The eggs are laid in the au¬ tumn, usually in the ground, and are hatched in the follow¬ ing summer. The greater number of the old crickets die on the approach of winter; a few, however, survive the cold season. Figure 135 represents the female of a species com¬ mon in the East. In this species the wings are shorter than usual. III. The Tree Crickets . — The common name of this group was suggested by the fact that these crickets are very apt to inhabit trees ; but they occur also on shrubs, or even on high herbs and tall grass. The most abundant species in the East is the Snowy Tree- cricket, CEcanthus niveus (GE-can'thus niv'e- us). This is a delicate, whitish-green insect, that lives upon shrubs or plants. The female often does serious damage by laying her eggs in raspberry canes, causing them to die above the puncture. Canes thus in¬ jured should be cut and burned in the early spring before the eggs are hatched. Figure 136 shows the male, his closely folded wings showing beneath his delicate transparent wing-covers. The female has her wing? covers wrapped closely around her body, making her look much narrower than the male. CHAPTER XIII. Order PHYSOPODA (Phy-sop'o-da). Thrips. The members of this order have four wings ; these are similar in form, long, narroiv, membranous, not folded, with but few or no veins, and only rarely with cross veins ; they are fringed with long hairs, and are laid horizontally along the back when at rest . The metamorphosis is incomplete . The mouth-parts are probably used chiefly for sucking; they are hit er mediate in form between those of the sucking and those of the biting insects (Fig. 138); the mandibles are bristle-like; the maxilla are triangular, flat , and furnished with palpi ; and the labial palpi are also present. The tarsi are two- jointed, bladder-like at tip , and without claws. Pull to pieces a clover-blossom or a daisy, and you will probably find at the base of the florets many wee, black, red, or yellowish insects. These are so small that it would take a dozen or more placed end to end to measure an inch ; and when disturbed they are apt to thrust the end of their bodies up in the air as if they meant to sting, looking as ferocious as such small insects can look. They are extremely lively, leaping or taking flight with great agility. Under a microscope their four narrow wings, delicately fringed all around with long hairs, may be seen ; these wings are laid flat down the back when at rest. The red ones are wingless, and are the young of the black species. Some species eat other insects, but most of them live upon vegetation. There is one species, Limothrips poaphagus (Lim'o-thrips po-aph'a- IIQ \ 120 THE STUD Y OF INSECTS. gus) that damages timothy and June-grass very much by working in the upper joints. In the early summer the dead and yellow heads of grasses thus destroyed may be seen everywhere in grass-growing regions. Some species live under the bark of trees. The accompanying figure repre¬ sents one of these insects very greatly enlarged (Fig. 137). Fig. 137. — Thrips. Fig. 138. — Mouth-parts of Thrips. (Drawn by J. 10. 130. — muuui-pans oi / /trips. ^ urawn Dy j. M. Stedman, under the author's direction .) 8, labrum; to, mandible; it, maxilla; 12, labium. The insect infesting grapes, called “The Thrips/’ is not a Thrips at all, but a leaf-hopper belonging to the Homoptera. The name Physopoda is from two Greek words : p/iysao , to blow up, and pous, a foot. It refers to the curious bladder-like feet of these insects. Figure 138 represents the mouth-parts of Thrips. CHAPTER XIV. Order Hemiptera (He-mip'te-ra). Bugs , Lice , Aphids , and others. The winged members of this order have four wings; in cne sub-order the first pair of wings are thickened at the base , with thinner extremities which overlap o?i the back ; in another sub-order the first pair of wings are of the same thickness throughout , and usually slope at the sides of the body. The mouth-parts are formed for sucking. The metamorphosis is incomplete. The order Hemiptera includes many well-known pests: here belong the true bugs, the lice, the aphids, the scale insects, and many other forms injurious to plants. On the other hand, some of the species are ranked among beneficial insects on account of their predaceous habits ; while still others, as the cochineal and lac insects, furnish us with useful products. The name Hemiptera is from two Greek words : hemi, half; and pteron , a wing. It was suggested by the form of the first pair of wings in the true bugs. Here the basal half of these organs is thickened somewhat like the wing-covers of beetles, only the terminal half being wing-like. The second pair of wings are membranous, and when at rest are folded beneath the first pair. The mouth-parts are formed for piercing and sucking. Without dissection, they usually appear as a slender jointed beak, arising at the base of a shorter, pointed upper lip. This beak consists of four bristles, enclosed in a fleshy, 121 122 THE STUDY OF INSECTS . jointed sheath (Fig. 139). Two of the bristles represent the mandibles, and two the maxillae. The sheath is supposed to consist of the labium and the grown-together labial palpi. In their transformation the Hemiptera pass through an incomplete metamorphosis; the young nymphs resembling F 1 g. 139.— Mouth-parts of Bug. (Af¬ ter Muhr.) Fig. 140, a. — Head of an heter- opterous insect. Fig. 140, b. — Head of an homopterous insect. the adults more or less closely in form, and the wings being gradually developed at successive molts. This order includes three well-marked groups, which are ranked as suborders. The first of these, the Heteroptera , includes the true bugs. They are placed first, as we believe they resemble the ancient Hemiptera — the first to appear on the earth — more closely than the members of either of the other suborders. The second suborder, the Parasitica, in¬ cludes the lice. These insects are much lower in structure than the Heteroptera; but we believe that this simplicity in structure is a result of degradation due to parasitic habits, and therefore really represents a later development than that shown by the Heteroptera. In other words, the lice are probably descendants of some ancient form resembling some of the existing Heteroptera. Among the Heteroptera the bedbug exhibits a similar downward tendency. The third suborder, the Homoptera , includes some forms that 1 HEMIPTERA . 123 are perhaps as primitive as any of the existing Heteroptera*, but, on the other hand, we find here forms that represent the widest divergence from the hemipterous type known to us. These three suborders can be separated by the following table : A. Wingless Hemiptera, parasitic upon man and other Mammals, with a fleshy, unjointed beak p. 147 . II. Parasitica. AA. Hemiptera with or without wings, but with a jointed beak. B. First pair of wings thickened at the base, with thinner extremi¬ ties, which overlap on the back; beak arising from the front part of the head (Fig. 140, a), p. 123 . 1. Heteroptera. BB. Wings of the same thickness throughout, and usually sloping at the sides of the body; beak arising from the hinder part of the lower side of the head (Fig. 140, it) P.J48.III. Homoptera. Suborder HETEROPTERA (Het-e-rop'te-ra). The True Bugs . People that know but little regarding entomology are apt to apply the term bug to any kind of insect; but, strictly speaking, only the Hemiptera are bugs, and many restrict the term to members of this suborder. We therefore des« ignate the Heteroptera as the True Bugs. The bugs are very common insects. They abound on grass and on the foliage of other plants. Certain foul-smell¬ ing members of this group are well-known pests in gardens, and upon berries in fields. In this suborder the first pair of wings are thickened at the base, while the tips, which overlap each other on the back of the insect, are thin and transparent ; and the beak arises from the front part of the head (Fig. 140, a). Some of the Heteroptera live in water, others on land, while still others live on the surface of the water or in marshy places. Each of these modes of life are characteristic of certain fami¬ lies. The name Heteroptera is from the Greek heteros , di¬ verse, and pteron , a wing. The following synopsis will aid 124 THE STUDY OF INSECTS . the student in learning the characters of the families of this suborder : SYNOPSIS OF THE HETEROPTERA. The Short-horned Bugs. Bugs with short antennae, which are nearly or quite concealed beneath the head. Bugs that live within water . The Water-boatmen, Family Corisida?:. (p. 129.) The Back-swimmers, Family Notonectid,e. (p. 130.) The Water scorpions, Family Nepid^e. (p. 130.) The Giant Water-bugs, Family Belostomid^E. (p. 131.) The Creeping Water-bugs, Family NauCORID.E. (p. 133.) Bugs that live near water. The Toad-shaped Bugs, Family Galgulid^e. (p. 133.) The Long-horned Bugs. Bugs with antennas at least as long as the head, and prominent except in the Phymatidce , where they are concealed under the sides of the prothorax. The Semi-aquatic Bugs. The Shore-bugs, Family SALDiDiE. (p. 134.) The Broad-shouldered Water-striders, Family VeliidjE. (p. 1 34-) The Water-striders, Family 1-Iydrobatid.e. (p. 135.) The Marsh -t readers, Family LiMNOBATiDiE. (p. 136.) The Land-bugs . The Land-bugs with four-jointed ante juice. The Thread -legged Bugs, Family EmesiDjE. (p. 136,) The Assassin-bugs, Family REDUVilDiE. (p. 137.) The Damsel-bugs, Family Nabid,e. (p. 138.) The Ambush-bugs, Family Phymatid>e. (p. 138.) The Flat bugs, Family Aradid^e. (p. 139.) The Lace-bugs, Family TingitiD/E. (p. 139.) The Bed-bug and the Flower-bugs, Family AcantkiiDjE, (p. 140). The Leaf-bugs, Family Capsid^E. (p. 140.) The Red-bug Family, Family Pyrrhocorid.e. (p. 141.) The Chinch-bug Family, Family Lyg^eid^e. (p. 142.) The Stilt-bugs, Family Berytid;e. (p. 143.) The Squash-bug Family, Family CoreiDjE. (p. 143.) The Land-bugs with five jointed antenncE. The Stink-bug Family, Family Pentatomid^e. (p. 144.) The Burrower-bugs, Family Cydnid^e. (p. 145). The Negro-bugs, Family Corimel,enid;e. (p. 146.) The Shield-backed bugs, Family Scutellerid,e. (p. 146.J HEM IP TER A% 125 Classification of the Heteroptera. (For adva7iced students.) In order to use the following table for determining the families of bugs, the student should become familiar with the names applied to different parts of the fore-wings of these insects. The thickened basal portion is composed of two pieces joined together at their sides ; one of these is narrow and is the part next to the scutellum when the wings are closed (Fig. 141, cl)\ this is distinguished as the clavus (claVus). ( “ The other broader part is the corium (co'ri-um) fig. i4t.— Diagram of (Fig. 141, co). The terminal portion of the wing- £ugg cover of a cover is designated as the membrane (Fig. 141, ?n.) In certain families a triangular portion of the terminal part of the corium is separated as a distinct piece; this is the cuneus (cu'ne-us) (Fig. 141, cu). In certain other cases, a narrow piece on the costal) margin of the corium is separated by a suture ; this is the embolium (em-bo'li-um) (Fig. 141,1). Fig. 145. Fig. 146. Fig. 1*7. Pyrrhocoridce . Ly gee id a. Core idee. TABLE FOR DETERMINING THE FAMILIES OF THE HETEROPTERA. A. Antennae shorter than the head, and nearly or quite concealed in a cavity beneath the eyes. B. Hind-tarsi without claws. C. Fore-tarsi flattened with a fringe of hairs on the edge, and without claws ; head overlapping the prothorax, p. 129. Corisidje. CC. Fore-tarsi of the usual form, and with two claws; head in¬ serted in the prothorax, p. 130 . NotonectiDjE. 126 THE STUD Y OF INSECTS. BB. Hind-tarsi with two claws. C. Caudal end of the abdomen furnished with a respiratory tube composed of a pair of grooved, thread-like organs, p. 130. NEPIDjE. CC. Caudal end of abdomen without respiratory tube. D. Legs flattened, fitted for swimming ; caudal end of the ab¬ domen furnished with a pair of strap-like appendages (these appendages are retractile and are frequently withdrawn from sight), p. 131 . Belostomidje. DD. Legs fitted for walking; abdomen without strap-like caudal appendages. E. Without ocelli, p. 133 . Naucorid«